"Save as" for macro editor

[klayoutmatthias]

See https://www.klayout.de/forum/discussion/1422/macro-development-window-no-save-as#latest for the original story.

[klayoutmatthias]

The implementation will provide a new entry in the macro tree's context menu: "Save As".

There is a tiny, but somewhat ugly effect: when a macro is Ruby, but it's saved to a Python folder, it won't change the interpreter. The folders are just categories, not imperative. Hence the "save as" feature needs to be used with a little care. Ideally, it's only use to save into the source folder to create a copy of a macro with a different name.