Add ExtractStrict and ExcludeStrict

[ekilah]

Fixes #37

I ran yarn format and picked up some changes in public.ts and in the index.d.ts.

Let me know if I should also include a version number change, or if you do that yourself when publishing.

(First time using dtslint, any tips welcome. I tried to do e.g.$ExpectType 'red' | 'green' | 'blue' for type PrimaryColors and it threw errors saying it got any instead. maybe this type of thing doesn't work in dtslint or I was using it wrong? edit: maybe i could try the suggestions here: microsoft/dtslint#179 if you want me to add more tests)

[ekilah]

I saw the CI errors locally too:

Error: /home/travis/build/pelotom/type-zoo/types/param-n.ts:11:1
ERROR: 11:1  expect  Expected type to be:
  {}
got:
  unknown
ERROR: 13:1  expect  Expected type to be:
  {}
got:
  unknown
ERROR: 43:1  expect  Expected type to be:
  {}
got:
  unknown

(unrelated to these changes)

[pelotom]

The CI errors are due to recent changes in TypeScript that make it so unknown is used as an upper bound instead of {} when a type parameter can't be inferred. So we should just switch the expectations to unknown.

[ekilah]

@pelotom seems to fail either way, using different TS versions?

[pelotom]

I pushed a fix to master. Basically we need to expect a minimum TypeScript version of 3.5 now.

[ekilah]

ah, there we go, thanks. lmk if the rest looks good when you have time!

[pelotom]

It looks good except the "Similar to Pick/OmitStrict but for types" language... I get the gist of what you're going for but all type operators are "for types". I'm not sure how to rephrase, but personally I would just drop this line because the "Similar to Exclude/Exclude but requires..." language is sufficient.

[ekilah]

Removed. thought it'd be nice for people unfamiliar with what the difference is between Pick and Extract, but that's not really the job of this repo I guess.

[pelotom]

Thanks!

[ekilah]

what's your publishing schedule for npm btw?

[pelotom]

Just published.