Rename test.h to pcut.h
Split into more headers
A bit of Doxygen comments
Add Doxygen configuration files
Move *_IMPL to headers where they are called
Reorder macros, hide them in user's doxygen
Try to enforce Doxygen documentation
gitignore for documentation
More documentation
Add some documentation
More documentation
Remove declarations of non-existent functions
Readme update
Merge branch 'headers-and-doxygen'

The merge reorganizes headers (from now on, #include <pcut/pcut.h> only)
and also adds a Doxygen documentation (for user and for developer).

The documentation still lacks proper intro page but otherwise it is
pretty healthy.