cleanup

- fix possible crash in conc (but it's still an ugly hack)
- fix noob usage of strcmp
- flag some memory leaks (it would be nice, if the author(s) would clean
   up the mess himself)
- fix crash in substr
- whitespace cleanup

there are plenty more memory leaks in command.cpp - for example, every
goto in cubescript does not clean up anything

source/src/worldio.cpp

@@ -590,4 +590,4 @@ bool load_world(char *mname)        // still supports all map formats that have
     return true;
 }
 
-COMMANDN(savemap, save_world, "s");
+COMMANDN(savemap, save_world, "s");