repo: added .mailmap

git shortlog now mirrors the names and email addresses in copying.md
Move finding python into separate CMake module.

See #40
Additionally CMake will find Python on OS X now. Fixes #16
Add OS X prerequesites section for OS X to building documentation
buildsystem: prettified the new findpython cmake module
Merge pull request #64 from svkurowski/add_osx_building_doc

Add OS X prerequesites section for OS X to building documentation