Resolve all TODO comments

[husio]

Resolve all TODO, FIXME and BUG comments. Either implement missing functionality or write a proper explanation of why certain functionality is not provided and what it means.

This is a huge task that requires a lot of product knowledge.

• context_test.go // TODO: test header context!
• architecture/NFT.md TODO: link to Isabella's two docs as background
• architecture/NFT.md TODO
• cmd/bnsd/client/tx.go // TODO: add fees, etc...
• cmd/bnsd/client/client.go // TODO: make this random
• cmd/bnsd/client/client.go // TODO: make this async, maybe adjust return value
• cmd/bnsd/client/client.go // TODO: something else?
• cmd/bnsd/client/main_test.go // TODO: check out config file...
• cmd/bnsd/app/app.go //TODO: Possibly revisit passing the bucket later to have more control over types?
• cmd/bnsd/x/nft/username/msg.go //TODO: This is being validated on model save
• cmd/bnsd/x/nft/username/handler_test.go //TODO: This needs to be extended with examples where we use approvals for different users
• cmd/bnsd/x/nft/username/handler_test.go //TODO: This needs to be extended with examples where we use approvals for different users
• cmd/bnsd/x/nft/username/msg_test.go // TODO: Add checks for approvals
• cmd/bnsd/x/nft/username/msg_test.go // TODO: Add checks for TokenDetails
• cmd/bcpd/app/init.go // TODO: anyone can make a token????
• coverage/upload.sh # TODO validate the yaml here
• errors/stacktrace.go // TODO: generalize better for other hosts?
• store/btree.go // TODO: reuse FreeList between multiple cache wraps....
• store/btree.go // TODO: reuse FreeList between multiple cache wraps....
• store/btree.go // TODO: currently noop....leave it to the garbage collector
• store/btree.go // TODO: add support for Combine (deleting those below)
• store/recorder.go // TODO: record new value???
• store/recorder.go // TODO: record new value???
• store/recorder.go // TODO: reuse FreeList between multiple cache wraps....
• store/helpers.go // TODO: make this private and only expose Iterator interface????
• store/iavl/adapter.go // TODO: make these configurable?
• store/iavl/adapter.go // TODO: create batch and reader and wrap the rest in btree...
• examples/mycoind/app/init.go return addr, "TODO: add a recovery phrase", nil
• abci.go //TODO: Implement when tendermint implements this properly
• coin/coins_test.go // TODO: verify constructor checks well for errors
• coin/coins.go // TODO: deprecate in favor of Coins.Combine()``
• orm/index.go // TODO: index name must be [a-z_]
• app/helpers.go // TODO: assert error if len > 1 ???
• app/helpers.go // TODO: support all prefix searches (later even more ranges)
• app/helpers.go // TODO: load normal iterator but then play it backwards?
• app/helpers.go // TODO: make this private and only expose Iterator interface????
• app/helpers.go // TODO: add reverse field
• app/store.go // TODO: is this correct? nothing else to do really....
• app/store.go // TODO: not implemented (ABCI spec still unclear....)
• app/store.go // TODO: support historical queries by getting old read-only
• app/store.go // TODO: better version handling!
• app/store.go // TODO: support proofs given this info....
• app/store.go // TODO: store the original validators somewhere
• app/store.go // TODO: investigate validators and consensusParams in response
• app/store.go // TODO: investigate response tags as of 0.11 abci
• app/store.go // TODO: investigate response tags as of 0.11 abci
• app/commit.go // TODO: this should probably be protected by a mutex....
• app/router.go // TODO: look for better trie routers that handle patterns...
• store.go // TODO: Get with proof, also historical queries
• store.go // TODO: add Batch to atomic writes and efficiency
• docs/tutorial/init.rst **TODO**
• docs/tutorial/datamodel.rst // TODO
• docs/tutorial/integration.rst **TODO**
• docs/tutorial/handler.rst by a Savepoint Decorator _,
• docs/tutorial/advanced.rst **TODO**
• crypto/ed25519.go // (TODO: look at sources of randomness, other than default crypto/rand)
• x/escrow/handler_test.go // TODO: add coins.Negative...
• x/escrow/handler_test.go // how to do a query... TODO: abstract this??
• x/escrow/model.go // TODO: code reuse???
• x/escrow/model.go // TODO: auto-generate sequence
• x/escrow/model.go // TODO: add indexes
• x/auth.go // TODO: remove duplicates (don't sort?)
• x/cash/dynamicfee.go TODO: If a transaction succeeded, but requested a RequiredFee higher than paid
• x/cash/staticfee_test.go return nil, errors.Wrap(errors.ErrHuman, "TODO: not implemented")
• x/cash/staticfee_test.go return errors.Wrap(errors.ErrHuman, "TODO: not implemented")
• x/validators/controller.go // TODO: improve this error message, so we use .New for stacktrace
• x/nft/approval_ops.go //TODO: Sort errors and their codes
• x/nft/approval_ops.go //TODO: Figure out what we need to do with counts for the next iteration
• x/nft/approval_ops.go //TODO: Figure out whether we need wildcard approvals, might be wise to add an ApprovalOptions flag
• x/nft/base/handler_test.go //TODO: Should we allow approved to remove their own approvals? :)
• x/nft/base/handler.go //TODO: revisit
• x/nft/approvals.go //TODO: Not sure I'm a fan of array of maps, but it makes sense
• x/nft/model.go //TODO: Better name
• x/sigs/controller.go // TODO: separate into own function (verify one sig)
• x/namecoin/token.go // TODO: remove??? On afterthought, this is probably never needed
• x/namecoin/handler_test.go // TODO: add queries to verify
• x/namecoin/controller.go // TODO: better enforce token presence and sigfigs
• x/namecoin/init_test.go // TODO: check tokens
• x/namecoin/handler.go // TODO: check that permissioning???
• x/namecoin/wallet_test.go // TODO: not enforced in bucket, but in handler (SetName)
• x/utils/key_tagger_test.go // TODO: also check delete
• commands/server/getblock.go // TODO: doesn't work on windows!
• query.go // TODO: implement

Acceptance criteria
The TODO, FIXME and BUG comments are resolved with one of two options:

• Functionality implemented
• Documentation explaining why functionality is not implemented