Add precompiled_header.hpp to target_precompile_headers
In !726 (merged) I deletied precompiled_header.cpp.
After some disscussion we found, that having just precompiled_header.cpp is not the proper way, how the precompiled header had to added to the cmake project - it has to be added to the target_precompile_headers section. Done
Edited by Yury Matveyev