editeng tiled rendering: fix selection overlay in Impress
editeng tiled rendering: fix selection overlay in Impress

The map mode is twips in Writer, that's why it worked there. For
Impress, we need a conversion to always have twips output.

Change-Id: I53c64b961180b6ff9b4ee75e3c5aa775416e7ae7

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core