[Patch] [Feature] Gradient Fill for Cells in Calc

[Markus Mohrhard]

Hey Muthu,

Two more points from me just as a notice.

You might run into two problems with the rendering code that are also
affecting the conditional format code.
The page preview and GDI Metadata currently don't work reliable
together with the background render code. My plan is to fix this as
soon as I have no more serious conditional format bugs for 3.6

Regards,
Markus