[Libreoffice] Merge of branch feature/unlimited-number-of-sheets to master

Hello all,

I just merged the branch feature/unlimited-number-of-sheets to master. This
only affects calc, but we did a lot of changes to the core of calc so if you
notice any problems with building or with functions that are not working as
expected please send me a short mail.

Calc should now be faster, but we were not able to remove the limit, only to
increase it 32000 sheets because uno and libs-gui still use sal_Int16 for
sheet index. But most important are the performance improvements, working
with several sheets should be much faster, and most operations with a few
sheets should be a bit faster too.

There are still some performance improvements I would like to do:
  - the undo code around sheet actions needs way to much memory
  - ScTable is misused for some actions
  - we call ScTabView::SetTabNo way to often when we perform a sheet action


Regards,
Markus