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/rendermodel.cpp

@@ -45,12 +45,12 @@ void mdlalphatest(int *alphatest)
 COMMAND(mdlalphatest, "i");
 
 void mdlalphablend(int *alphablend) //ALX Alpha channel models
-{ 	 
+{
     checkmdl;
     loadingmodel->alphablend = *alphablend!=0;
 }
 COMMAND(mdlalphablend, "i");
-	 
+
 void mdlscale(int *percent)
 {
     checkmdl;