Fixes: lp:1785879 * https://bugs.launchpad.net/kicad/+bug/1785879
Drop all uses of wxRAISED_BORDER and wxSUNKEN_BORDER from dialogs and panels used in main frame windows. Drop use of wxSP_3DSASH options on all wxSplitterWindow definitions. Minor dialog alignment and spacing fixes.
(cherry picked from commit 08b4463)
(cherry picked from commit 8ee3e77)