Use the full words for parameters in color methods, not just
`r` and `g`. This make our definitions more self-documented and
allow us to remove @param from comments. This commit also fix
other minor issues.
Notable changes:
- Move index.d.ts from types/ to project root (needed for
tsd-check module).
- Rename test.ts to index.test-d.ts and place it under root
(needed for tsd-check module).
- Add tsd-check module to test Typescript Definitions.
Future Work:
The properties inverse, hidden, strikethrough and visible
of Chalk interface in index.d.ts needs to be documented.
