Deleted the now useless 'types.hpp' file.

All types defined in that file were not used anymore. Removed legacy
code using those types in a few files.
Unit tests: removed the now unused 'isPNG' function in the image tests.
UEye_Camera: removed unused macros.
Documentation fixes.

The documentation now compiles without warnings!
Makefiles: Added a 'make test' command.

This command compiles and runs the unit tests from the main Makefile.
Merge branch 'refactoring'