Unify build versioning

[jkulawik]

At the moment, there's several build ID headers that had to be generated with some external tool.

These should be unified / updated to not compile the editors with a 2010 date.

This article describes how it could be done using CMake.

[jkulawik]

I can't get CMake's add_custom_command to work. Also the original build systems needs way too many extra files, requires perl to work, only updates the IDs when CMake is ran, and generates VCS changes with each build.

It seems like it would be much better to use C++ precompiler macros: https://stackoverflow.com/questions/17739390/different-format-of-date-macro

This has the benefits of:

• no diffs generated
• no extra dependencies
• allows me to get rid of the ~20 files that are needed for build IDs

The macro could be inserted directly into the editor files instead of separate header+cpp files, and only a utility function for converting the format would be needed (would probably need to be put in core).

CMake's configure_file can also be used, but has similar disadvantages to the current approach.

[jkulawik]

There's also buildcounterinput.txt files which are used in VS project files, not sure what to do with those. Although those project files definitely have to be regenerated anyway.

[jkulawik]

Split that to another issue, this one is done.