… order to avoid having to use custom pak content

…p yet)

…ysics with player not working correctly

The old hack replaced "#define GAME_FPS 60" and the similar defines for
GAME_FRAMETIME and CHAINGUN_FIRE_SKIPFRAMES with in the scripts with
other values based on com_gameHz, for example to "#define GAME_FPS 144".

This has two disadvantages:
1. When changing com_gameHz, you'll have to reload the scripts
2. This changes the checksum of the scripts, so each time you change
   com_gameHz the checksum changes and your old savegames stop working.

Luckily the scripts already have functions (that are implemented in the
gamecode) that expose the FPS and FrameTime: sys.getTicksPerSecond()
 and sys.getFrameTime()

So now we modify the #defines to call those functions instead.
That will still break *old* savegames, but at least savegames made from
now on will still work no matter what you set com_gameHz to.

adjusted to use gameLocal.gameHz instead of USERCMD_HZ, of course

thanks to Github user tyuah8:
dhewm#584 (comment)