MT#7861 Use pixels as main unit to be in accordance with svg-edit.

(cherry picked from commit bdd8562fb0ee0a98cb1296822fa1e211fa0d8c5f)
MT#7867 Return scale 0.8 untill other options tested with real printing

(cherry picked from commit 0fbbcf663714153e702cea2d4ffbfba24e0f107c)