Build 173936 for Serious Sam 3 is released.

- Linux: Various fixes for visual artefacts caused by GPU resource corruptions that happened when game was minimized, alt-tabbed or otherwise lost focus.
- Faster switching into game after Alt-Tab, and changing Gfx APIs.
- Linux: Outdated driver versions are now reported to user on Linux.
- Linux: Fixed zombie processes sometimes being left over by the game.
- Fixed problem where correct video mode wasn't started when changing back to game (via alt-tab) if cvar 'gfx_iAPI' is set to gfx API that is not actually supported by the platform.
- Added CPU name detection and output to console.
- For detecting GPU vendor and device ID under Linux, "lspci" external command is now used instead of "libpci" interface.
- OSX: Some fixes for handling of gained/lost keyboard focus.
- Prevented possible application crash that may occur during Steam Workshop sync IO failure.
- Handling of GPU synchronization (if gfx_iFinish>0) is now more responsive. It would sometimes cause stuttering previously.
- FPS counter variation is now also displayed (minimum and maximum frame rate for last refresh interval). Controlled via 'prf_bShowFPSVariation' cvar. (Default is on.)
- Fixed crash at start if Steam is running in offline mode.
- Mouse is no longer confined to window after alt-enter.