GUI: Extracted Liberation fonts from fonts.dat and mention them in the licenses

Author: sev-

COPYING.OFL

@@ -1,5 +1,13 @@
-NOTE: This license file only applies to the Source Code Pro font file:
-"SourceCodeVariable-Roman.ttf" distributed along with our theme files.
+NOTE: This license file only applies to the fillowing files distributed
+along with our theme files:
+
+ * SourceCodeVariable-Roman.ttf
+ * LiberationMono-Bold.ttf
+ * LiberationMono-Regular.ttf
+ * LiberationSans-Bold.ttf
+ * LiberationSans-Regular.ttf
+ * LiberationSerif-Bold.ttf
+ * LiberationSerif-Regular.ttf
 
 Copyright 2010, 2012 Adobe Systems Incorporated (http://www.adobe.com/),
 with Reserved Font Name 'Source'. All Rights Reserved. Source is a