issue #35: Issues with Dark LAFs (f.e. Dark Metal)

[ui] updated custom forms/options to be compatible to dark themes
introduced in NB74 (labels use correct colors, tooltips use link color,
all tables use default colors, buttons have size height, ...)
[ui] redesign of optionpanel - resizes correctly now
Merge pull request #37 from markiewb/bugfix/fix_35

issue #35: Issues with Dark LAFs (f.e. Dark Metal)