Finished base management for volumetric features. Code compiles, but this feature is not tested so far!

Made CVARs for volumetric features module.
Made trigger delay attribute for volumes, per player. Count down for n seconds after when a player enter. When leaving a volume trigger delay is aborted.
Made parameter parsing functions; paramtools.inc.
Made functions for setting and parsing generic volume attributes.
Updated header in files to volumetric features and paramtools.inc.
Removed unused knockback functions in zadmin.inc.
Made certain class functions into stock functions.

src/zr/zombiereloaded.inc

@@ -116,7 +116,7 @@ stock bool:ZRIsClientValid(client, bool:console = false)
  */    
 stock bool:ZRIsConsole(index)
 {
-    // Return true if index is = to console's index.
+    // Return true if index is equal to console's index.
     return (index == ZR_CONSOLE_INDEX);
 }