added gtest & catch2, with auto download.
refactored cmake tools.
refactored pkg managers and tests so that using them in CMakeLists.txt is reason enough to load them.
added ccache.
reworked readme.
reworked error messages in case of missing elements (with install suggestions).
fixed edge case of cleaning when no build has occured in ./build.sh.
added benchmark example for catch2.
added gtest & catch2, with auto download. refactored cmake tools. refactored pkg managers and tests so that using them in CMakeLists.txt is reason enough to load them. added ccache. reworked readme. reworked error messages in case of missing elements (with install suggestions). fixed edge case of cleaning when no build has occured in ./build.sh. added benchmark example for catch2.