Remove useless checks for nil

http://alltom.com/pages/objective-c-nil-is-the-best
Improve API
Remove useless #import
Convert APTextField subclass to a simple category
API for selectedToken
Pretty typedef for token finding
Move some methods around
Annoying whitespace
Disambiguate some method names
Improve handling of token selection
General improvements of logic

- Move resultsTable reload and delegate call to addToken method
- Less ambiguous token removal
Even less ambiguous token removal!
For friendlier API:

Partial revert of commit 6cd05b69b540f11b510c0c9c7979d83f0c5a9cc6 (Disambiguate some method names)
Extend delegate with didTapToken protocol method
Use same background color for results table as Apple uses
Flash token
API for allowDuplicates
Improve code flow for selecting tokens and activating textfield
Annoying whitespace
Fix bug that would cause textfield to stay disabled forever (see line 529)