small fixes

incident constraint visual added

Incident constraint fixed

some fixes

some fixes

some fixes

incident constraint visual added

Incident constraint fixed

some fixes

some fixes

some fixes

perpendicular constraint fixed

parallel visual fixed

Parallel constraint fixed, parallel visual added

Constraint manager fixed, parallel constraint fixed

Names fixed

some fixes

arc editor added

Ellipse editor added

circle editor added

Names fixed

some fixes

arc editor added

Ellipse editor added

circle editor added

Delete button added