This adds support for 32 pixel icons - mainly to get them into
the toolbar.

Most changes made are to change the behavior of having only small
and large icons as a boolean choice, but not every code path was
converted to non-boolean choice yet.

Breeze icon theme has the 32px variants so it can be used already.

Change-Id: Iadf832a87826c16b3a83522104dd6c35d61a0f87
Reviewed-on: https://gerrit.libreoffice.org/30398Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>