Making sure all line endings will be LF

Added .gitattributes to make sure all line endings wil stay LF
Merge pull request #20 from mbed67/line_endings

Making sure all line endings will be LF
Added more files that should be normalized
Merge pull request #21 from mbed67/line_endings

Added more files that should be normalized
Added keywords abstract and final to class info

This solves the following issues: new-black 18 and 22 and zend 12 and 16
Merge pull request #22 from mbed67/abstract_final

Added keywords abstract and final to class info