Prepare for a new Slovenian translation.
Add Slovenian translation (ticket #3643).
"Output" property page: Remove some dead code.
"Output" property page: "Shader" and "Rotation" were sometimes wrongly displayed as unavailable for "Sync renderer".

This commit fixes #3672.
Use UINT_MAX instead of -1 casted to UINT when the doc mentions 0xFFFFFFFF.
Use conversion constructors to work-around confusing AStyle styling.
FakeFilterMapper hooks: Document the check for "negative" registry key handles.
Improve the Get(Cur)DispMode and SetDispMode functions.

Fixes CID #966222.
Use a bitcheck instead of casting (WIP).

Fixes CID #965944.