Precompilation of prefix header for GCC and Clang requires some efforts thanks to CMake which doesn't support this feature out of the box
Existing thirparty solutions must be tuned to our needs, and our configuration should be adjusted to a chosen module
- a bit of header cleanup.
* moved <zlib.h> and <bzlib.h> from files.h to files_decompress.cpp because they are no longer needed for defining the interface.
* added <functional> to the precompiled header
There's simply never enough of them and they are used far too infrequently to justify the hassle of tagging along two TMaps per class.
For what they provide, single global lists that handle all player classes at once are fully sufficient.
