Refactored: Factorified DiffIterator.
Refactored: Inject ReflectionLookup. #16
Implemented #16: Caching of staticReflection results per revision.

This gains more than 50% performance. My X220 now analyzes Twig in 19 mins.
Fixed #15: Explained labeling mechanism more extensively.
Added: Basic .travis.yml. #11
Fixed: Removed PHP 5.4 from .travis.yml. #11

Using generators in some places.
Fixed: Tests after refactoring.
Fixed: Split up Travis test commands.

This should hopefully fix that travis calls a build successful even if
PHPUnit fails.
Added: Travis build state to README.
Merge branch 'master' of https://github.com/Qafoo/changetrack into composer
Added dev requirements again to composer.lock for Travis
Added --no-dev parameter to install instructions