Move "Configure-Xastir" to "File-Configure", clean up operating pages
"Configure-Xastir.md" was not about configuring Xastir, it was
documentation of the File->Configure menu. This was a misleading name
and caused more than one person confusion in writing documentation and
linking to it (me included, after a long night of pounding out
documentation).
I renamed it to something that actually reflects the contents of the
file, "File-Configure.md"
Cleaned up the Operating Quickstart and Operating pages to make them
not say things like "we should document that" when we in fact are
documenting it already.
Added text and links concerning using the map window in the Operating
page.
