* Arguments for max number of parts and tiles to render (optional).
  + Automatic estimation of maximum tiles to render based on max parts
    for Writer docs, since there is only 1 part, this caps the number
    of pages to render, similar to other doc types.
* Fixed rendering of Writer documents over and over (as many times as pages).
  + Writer has a single part, unlike other doc types.
  + No point in rendering the whole document in writer to a single tile,
    since that's completely unrealistic and impractical (it takes
    forever for large docs and artificially spikes the memory).
* Rendering starts at the current part and not the first.
  + This gives the spreadsheet of interest priority (if saved as visible).
* The tile size is now more realistic as we use the same dimensions
  as the Online client does.
* When rendering tiles at scale, we use the same dimensions as the
  Online client rather than splitting the width by 4, for realism.
* Rendering of tiles is done rows-first, rather than columns-first,
  which is similar to what the Online client does, which is more
  cache friendly, therefore more realistic.
* Enabled compiling of tilebench when GTK3 is disabled, which
  was erroneous, since tilebench doesn't have any dependency on GTK.
  + Now it's possible to compile with local Cairo/Pixman libs.

Reviewed-on: https://gerrit.libreoffice.org/44936Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>
(cherry picked from commit 7db98521)

Change-Id: I6ad2e97f39572778dd7d0c12d14550841c1d6963
Reviewed-on: https://gerrit.libreoffice.org/46984Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>