The sources here are a slighly simplied version of
gtksourceview version 1.8.5 (March, 2007)

They incorporate a couple of changes for use with gretl.

* Location of the "language spec" directories: we use the
  registry on Windows, and we consult the environment variable
  GTKSOURCEVIEW_LANGUAGE_DIR on non-Windows systems.

* Escape character: we mark "\" as escape, but we exempt 
  newline from being escaped in the context of a gtksourceview
  regex.  That way, we prevent the "line comment" coloration
  from bleeding over onto backslash-continued lines.


