File extensions white list

If not empty, only files with these extensions will be indexed.

If an extension is in both whitelist_exts and blacklist_exts, the blacklist will prevail and the file will be ignored.

Property definitions

vsm $ FileIndex :: whitelist_exts
	# File extensions white list
	#
	# If not empty, only files with these extensions will be indexed.
	#
	# If an extension is in both `whitelist_exts` and `blacklist_exts`, the
	# blacklist will prevail and the file will be ignored.
	var whitelist_exts = new Array[String] is writable
lib/vsm/vsm.nit:323,2--329,51