Progress indication on export

[dfreeman@…]

Since generating a DVI/PDF etc. can take a long time, especially on the first go
since the cache is empty, there should be a progress indication.

I suggest a progress bar along the bottom of the main window, or a separate
dialogue box to let you know that a) something is happening, and b) which steps
are done and yet to do.

Also the mouse pointer doesn't change to a busy pointer immediately as it should

• there is a noticeable delay on slow computers. I have been in a situation

where I wasn't at all sure if anything new was happening. Possibly this is when
the figures are being processed for the first time.

[Uwe Stöhr]

Valid request but extremely difficult to achieve because it strongly depends on
your LaTeX-system and the packages you are using in the preamble.

I would say WONTFIX.

[ps@…]

and will be fixed in a way once we have #412 solved.

[ps]

lets say dupe of #412