* add package lock creation * change target name * fix cpm_export_variables * add test * fix git repo detection addition * remove test package lock from git * add link to package lock wiki * add CPMGetPackage
* create FindXXX.cmake modules for added CPM packages * don't use list(PREPEND) as it unsupported on older CMake versions * use CMAKE_BINARY_DIR * ensure CPM.cmake is initialized only once * import CPM.cmake in modules
* add support for SOURCE_DIR argument * simplify code * add test * update comment
