Tests for improvement in rendering

[Regina Henschel]

Hi all,

I have a first version of a patch for
https://bugs.documentfoundation.org/show_bug.cgi?id=140321
"Fontwork: Change in surface has no effect"
in Gerrit
https://gerrit.libreoffice.org/c/core/+/124720

The improvements are about rendering. I'm looking for a partner, who can 
write tests for it.
Solved problems are:
Shape was rendered with specular light, should be matte.
Shape was rendered the same in surface 'matte', 'plastic' and 'metal'. 
Should be three different renderings.
Shape was rendered with shade mode 'flat' in all cases, which produces 
steps. Should be rendered smooth in case of shade mode 'gouraud'.

Kind regards,
Regina