XUL snippets set is no longer supported

Starting with version 2.30, the XUL snippet set is no longer supported. Instead, there is GWC for Silverlight, which covers the same kind of usage as the XUL snippet set, but with a more powerful technology.

Following OS are no longer supported: osf0510, sco0507 and uxw0711

These Operating Systems (HP Tru64 unix V5.1B, SCO OpenServer 5.0.7 and SCO UnixWare 7.1.3 - 7.1.4 & OpenServer 6.00) are very old and do not fit with the minimal OS requirements needed for the GAS redesign (specifically multi-threading).