Convert project to TypeScript

Changes to resolve the many (~50) compile errors turned out to be:
- Mostly be a matter of adding type definitions in new .d.ts files to resolve method/property missing error spam.
- Also a matter of adding a few type annotations to "prove" the safety of things to TypeScript.

Gratuitous changes:
- Renamed client.js -> trello-client.js
- Added more type definitions than necessary.
- Whitespace consistency fixes.

Bugs caught:
- Called $.grep with 2 arguments, 3rd ("inverse") wasn't intentionally optional.

Generated Javascript still looks basically identical to the original, ignoring the tons of whitespace changes and a few removed comments here and there when postfixed to a line.