new ToggleBox widget

Hi I made a Togglebox widget descended from TfpgComboBox. It has button
that slides side to side for checked/unchecked with a subtle animation
when toggled. Various colors can be changed and the animation disabled.
uidesigner: added togglebox widget to the palette bar
toggle: fixes minor bug where selected font isn't used.
Merge branch 'ah/togglebox' into develop