Add new public var with mapname and new constant (#687)

* Add new public var with current map name

* Add a constant to define max map's name length

* Reducing the maximum buffer size to store a map's name

* The PLATFORM_MAX_PATH constant replaced to MAX_MAPNAME_LENGTH

plugins/include/amxconst.inc

@@ -29,6 +29,11 @@
  */
 #define MAX_STRING_LENGTH 16384
 
+/**
+ * The maximum buffer size required to store a map's name.
+ */
+#define MAX_MAPNAME_LENGTH 64
+
 /**
  * Defines and constants related to the maximum number of clients.
  *
@@ -44,6 +49,11 @@
  */
 public stock const MaxClients; 
 
+/**
+ * Current map name
+ */
+public stock const MapName[MAX_MAPNAME_LENGTH];
+
 /**
  * Pass this into certain functions to act as a C++ NULL 
  */