Hopefully fixes #1677 and its duplciates.

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3722 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834
- added PCH compilation for CMake using cotire module (PCH is OFF per default, can be enabled with ENABLE_PCH=ON)

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3723 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834
- added missing cotire files to previous commit

git-svn-id: http://svn.code.sf.net/p/vcmi/code/trunk/@3724 4dfc6b2a-8b31-0410-aa91-d6c70e3ac834