🚀 Performance improvements using cache

Big thanks to @DaVarga for creating the PR which improves performance.
Windows users should get MUCH better results now!

• Fix tests and refactor 6ef43e7
• Merge pull request #3 from DaVarga/master f2192de
• Performance: implement preprocess to skip untouched files 24b5716
• Performance: implement memoization for git diff 6e4656e

v1.0.3...v1.0.4