Fixed nasty bug where radius was miscalculated for circles

In the case where scale doesn't start at 0, this gave back the wrong value for radius of a circle.
Did the math right.
Initial radiogroup widget
numbering formats for the choices (number, latin-upper, latin-lower,none)
Merge pull request #37 from mlippert/widget-refactor

initial work on radio button widget
small updates to mc
Merge branch 'upstream/master'