Fix inconsistencies with buffer sizes for player names.

Found any I could not using MAX_NAME_LENGTH and changed them to use it. I think that we should
increase MAX_NAME_LENGTH to 128 for CS:GO at some point as that's what it uses internally.
(Presumably to get the client's full multibyte name from Steam without truncation mid-codepoint which
can happen in other games. Steam's max is 32 characters if I remember correctly, but allows multibyte chars).

plugins/playercommands/slap.sp

@@ -149,7 +149,7 @@ public MenuHandler_Slap(Menu menu, MenuAction action, int param1, int param2)
 		}	
 		else
 		{
-			decl String:name[32];
+			decl String:name[MAX_NAME_LENGTH];
 			GetClientName(target, name, sizeof(name));
 			PerformSlap(param1, target, g_SlapDamage[param1]);
 			ShowActivity2(param1, "[SM] ", "%t", "Slapped target", "_s", name);

plugins/playercommands/slay.sp

@@ -103,7 +103,7 @@ public MenuHandler_Slay(Menu menu, MenuAction action, param1, param2)
 		}
 		else
 		{
-			decl String:name[32];
+			decl String:name[MAX_NAME_LENGTH];
 			GetClientName(target, name, sizeof(name));
 			PerformSlay(param1, target);
 			ShowActivity2(param1, "[SM] ", "%t", "Slayed target", "_s", name);