Added shorthand units to UnitType

[dotlouis]

Thanks for this useful library!

When using Typescript, shorthand units were throwing errors because not recognized.

On a side note, I wonder if the same type (UnitType) should be used for set() and add()/subtract()methods. Because the former does not take a week as a unit (which would count as valid in TS typings). Just a thought.

[codecov-io]

Codecov Report

Merging #470 into dev will not change coverage.
The diff coverage is n/a.

@@         Coverage Diff         @@
##            dev   #470   +/-   ##
===================================
  Coverage   100%   100%           
===================================
  Files        53     53           
  Lines       470    470           
  Branches     72     72           
===================================
  Hits        470    470

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update c4517a8...2c9256f. Read the comment docs.

[iamkun]

@dotlouis thanks you are right, and advice here? Or just copy to another unitType?

[dotlouis]

Well you can make union types to avoid copying code. Something in the likes of:

type OpUnitType = 'day' | 'hour' // ... all common unit types
type SetUnitType = OpUnitType | 'week' // all additional types

I can make a PR with the changes if you'd like