Reorganizing server-side source code: entities, monsters and weapons

[SNMetamorph]

Originally, in HLSDK bunch of code was clumped in single .cpp files with thousands lines of code in them. That isn't easy to maintain and understand, especially for beginner developers. Also less clumped structure of source code will lead to better compiling time, since different translation units may being compiled simultaneously. In final, every generic entity and weapon will be located in separate pair of source files: modifying existing and adding new objects will be relatively easy.

[SNMetamorph]

Rest of the files that need to be splitted:

• [x] effects.cpp
• [x] maprules.cpp
• [x] physents.cpp
• [x] plats.cpp
• [ ] player.cpp
• [x] triggers.cpp
• [x] scripted.cpp
• [ ] subs.cpp