Fix TEX_SPECIAL assignment for liquids

[SirYodaJedi]

When Valve changed the character that defines liquids from * to !, they left the check for assigning the TEX_SPECIAL flag as asterisk, resulting in liquids always getting 240tx subdivision and lightmaps, unlike Quake.

SDHLT/src/sdhlt/sdHLCSG/textures.cpp

Line 808 in 9a9c879

if (bt->name[0] == '*'

This is a bit wasteful in vanilla renderers, since they don't support lightmapped water, so the check should be changed to set the flag for ! textures as well, unless you pass a -litwater param to CSG (for use with custom renderers). I suppose * textures should still receive this flag, for consistency with vanilla behavior, but I'm not sure if that's too important (idk what happens if a non-liquid gets this flag).

(Also, the length defined for env_sky's strncasecmp should be 7, not 5.)