Merge some file writing extension checks from OpenJK.

Thanks Ensiform.
https://github.com/JACoders/OpenJK/commit/05928a57f9e4aae15a3bd0
https://github.com/JACoders/OpenJK/commit/ef124fd0fc48af164581176
qboolean Com_FieldStringToPlayerName( char *name, int length, const char *rawname )
{
	char		hex[5];
	int			i;
	int			ch;

	if( name == NULL || rawname == NULL )
		return qfalse;

	if( length <= 0 )
		return qtrue;

	for( i = 0; *rawname && i + 1 <= length; rawname++, i++ ) {
		if( *rawname == '\\' ) {
			Q_strncpyz( hex, rawname + 1, sizeof(hex) );
			ch = Com_HexStrToInt( hex );
			if( ch > -1 ) {
				name[i] = ch;
				rawname += 4; //hex string length, 0xXX
			} else {
				name[i] = *rawname;
			}
		} else {
			name[i] = *rawname;
		}
	}
	name[i] = '\0';

	return qtrue;
}

qboolean Com_FieldStringToPlayerName( char *name, int length, const char *rawname )
{
	char		hex[5];
	int			i;
	int			ch;

	if( name == NULL || rawname == NULL )
		return qfalse;

	if( length <= 0 )
		return qtrue;

	for( i = 0; *rawname && i + 1 <= length; rawname++, i++ ) {
		if( *rawname == '\\' ) {
			Q_strncpyz( hex, rawname + 1, sizeof(hex) );
			ch = Com_HexStrToInt( hex );
			if( ch > -1 ) {
				name[i] = ch;
				rawname += 4; //hex string length, 0xXX
			} else {
				name[i] = *rawname;
			}
		} else {
			name[i] = *rawname;
		}
	}
	name[i] = '\0';

	return qtrue;
}
