misc: todos, .gitignore, cleanups, broken links, readme, milestones, grammar

[wthrajat]

Making a PR only for updating the milestone would be an overkill so I made some quick fixes alongside.

1. Fix todo: publickeys magic numbers are now not hardcoded.
2. Fix todo: unwrap to Result for better error handling.
3. We now don't need */temp-files in .gitignore.
4. Docs run_teleport.md and developer_resources.md have been renamed, but not at all places. Also we should use relative URLs instead of hardcoded. They work bad when in branch other than master and in forks.
5. Remove old information in src/protocol/messages.rs
6. Milestone and readme.

[codecov]

Codecov Report

Attention: 20 lines in your changes are missing coverage. Please review.

Comparison is base (e6dcd03) 68.86% compared to head (0a3f69c) 68.80%.

Files	Patch %	Lines
src/scripts/wallet.rs	0.00%	17 Missing ⚠️
src/wallet/direct_send.rs	0.00%	1 Missing ⚠️
src/wallet/funding.rs	0.00%	1 Missing ⚠️
src/wallet/swapcoin.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #89      +/-   ##
==========================================
- Coverage   68.86%   68.80%   -0.06%     
==========================================
  Files          28       28              
  Lines        5771     5773       +2     
==========================================
- Hits         3974     3972       -2     
- Misses       1797     1801       +4     

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[rajarshimaitra]

ACK 0a3f69c