launcher improvements

[maksw2]

in csgo and new tf2 instead if hl2.exe we have gamename.exe.
these games didn't require the -game parameter to launch, so i'm asking is it possible to make double clicking hl2_launcher.exe directly launch the game (--build-games= would also change the launcher to default not to hl2 folder but to build game folder).

[maksw2]

looks like i found the line.

[DiegoArmando-27]

DEFAULT_HL2_GAMEDIR is defined at line 94 if someone needs

[maksw2]

can we derive this from --build-games ?