Update of Draft code that may cause problems for external workbenches

[vocx-fc]

The structure of the Draft workbench in FreeCAD 0.19 is being updated so that it is easier to manage the large code base. Therefore, some modules have been renamed and moved around.

This issue tracks problems in Dodo as the new Draft code is merged into the master branch.

The first pull request made to solve a problem was #4.

Some pull requests that may affect the tools of Dodo are

• Draft: re-organization of the snap code FreeCAD/FreeCAD#3091 (snapper and snap commands).
• Draft: re-organization of the trackers code FreeCAD/FreeCAD#3092 (trackers)
• Draft: organization of select plane code FreeCAD/FreeCAD#3094 (SelectPlane)
• Draft: improvements in working plane and plane proxy creation FreeCAD/FreeCAD#3157 (WorkingPlane)

The general organization of the new code is described in this forum thread: [Discussion] Splitting Draft tools into their own modules.