This PR improves the behavior of the Draft grid:
* Options in the preferences: "Always show the grid" and "Show the grid during commands".
* The parameters are used for new views. In existing views the grid can be toggled either during a command or when no command is active.
* When switching to a different workbench all grids are hidden unless GridHideInOtherWorkbenches is set to `False`. This can be a Fine-tuning parameter IMO.
Notes:
* The defaultCameraHeight parameter becomes obsolete. It was only used in very specific circumstances.
* The code of PR #8818 becomes obsolete. It makes more sense to use `App.activeDraftCommand` instead of adding a `tool` argument to some functions. Will do some related cleanup later.
* Improved alignment for the related preference ui. The checkbox interaction has been fixed as well.
- If grid is on and auto grid on: Grid always appears
- If grid is on and auto grid off: Grid off at start, on when using a tool, off afterwards
- If grid is off: Grid never appears
In Python 3 `super()` can be used without an argument
in order to get the parent class, `super()`.
In Python 2 the present class must be used as an argument,
`super(ThisClass, self)`.
This commit is done to support Python 2,
as without it all Gui Command tools will be broken
and will fail to launch, even if the unit tests pass.
Also, set the `__metaclass__` variable to `type`.
This is done to turn all classes into "new style" classes
in Python 2. This is required so `super()` works correctly
in this version of Pyton.
This commit can be reverted once Python 2 support
is completely dropped, and only Python 3 compatible code
is used.
