(svn r3564) Several smaller changes:

- Don't treat non-booleans as booleans
- Reduce variable scope
- Bracing
- Use DeMorgan's law to make conditionals easier to read
- if cascade -> switch
- Replace some magic numbers by symbolic names
- Avoid assignments within other statements

sound.c

@@ -102,7 +102,7 @@ static void OpenBankFile(const char *filename)
 
 static bool SetBankSource(MixerChannel *mc, uint bank)
 {
-	FileEntry* fe;
+	const FileEntry* fe;
 	int8* mem;
 	uint i;