Add initial UnrealScript support

The two samples are for two different UnrealScript generations:
MutU2Weapons is UnrealScript 2, US3HelloWorld is UnrealScript 3.

Signed-off-by: GreatEmerald <pastas4@gmail.com>

lib/linguist/languages.yml

@@ -1513,6 +1513,12 @@ Unified Parallel C:
   color: "#755223"
   primary_extension: .upc
 
+UnrealScript:
+  type: programming
+  color: "#a54c4d"
+  lexer: JavaScript
+  primary_extension: .uc
+
 VHDL:
   type: programming
   lexer: vhdl