Merge pull request #6 from eggrobin/quantities-tests

Quantities tests
h -> hpp in Quantities.
h -> hpp in Geometry.
h -> hpp in QuantitiesTests.
h -> hpp in CTSGeometryTests.
Maybe GitHub recognises .ipp?
Rename SI.ipp to SI-inl.hpp
Make GitHub happy.
Merge pull request #7 from eggrobin/change-extensions

Change extensions
No space at end of line.