add harelang

..to a "generated" file, I know.
harelang is not likely to be accepted by github/linguist right now, as
they like to see a new language being actively used first (at least 200
unique :user/:repo combinations). this allows for building against a
custom go-entry directly, if needed, for now.

data/extension.go

@@ -431,6 +431,7 @@ var LanguagesByExtension = map[string][]string{
 	".gypi":                {"Python"},
 	".h":                   {"C", "C++", "Objective-C"},
 	".h++":                 {"C++"},
+	".ha":                  {"Harelang"},
 	".hack":                {"Hack"},
 	".haml":                {"Haml"},
 	".haml.deface":         {"Haml"},