+ support adding circles as external geometry not lying on the sketch plane
+ port to CMake 3.0
+ fix saving problem with file names containing an apostrophe
+ fix crash when dragging a point adter undoing the deletion of a line
+ whitespace improvement
+ fix inconsistency problem after undo/redo
Sketcher: Slot: proper tangent constraints

Endpoint-to-endpoint tangency is applied now instead of
tangency+coincident.
Fixes issue #0001828 ( http://freecadweb.org/tracker/view.php?id=0001828
)