hidpi: Sidebar, fontwork, autoformat and other improvements.

This is a second batch of HiDPI changes. It fixes the following areas:

Sidebar
* Impress Master pages preview
* deck title height
* tab (icon) bar
* valueset dropdown control
* wider maximum width
* Draw and other misc. buttons which didn't get fixed by earlier
   change to Toolbar.SetItemImage
There are several more sidebar issues, but it is much improved.

Other changes
* Writer and Calc auto-format dialog text
* file-properties document image
* fontwork gallery preview size
* Calc table border control

Change-Id: I95a0169a3b011836b1c75b3dcacb2733c9567ef3
hidpi: Blind fix - avoid double scaling by updating GetItemImage().

I guess some code uses GetItemImage(), and then SetItemImage() again.  To make
it work, scale the image down in the hidpi mode.

Change-Id: I1ce9fdb28564b829253d7a9c7eabb46019e68876