For Blender builtin configurations the option to choose the select mouse remains
and is now also in the splash screen. It works by changing the keymap dynamically
in the script, rather than using special events.
The system of automatic switching of events was not flexible enough to deal with
side effects that require further keymap changes, so it is now under more manual
control in the script.
This breaks compatibility for some scripts and exported key configurations.
These can be fixed by replacing SELECTMOUSE, ACTIONMOUSE, EVT_TWEAK_S and
EVT_TWEAK_A with appropriate LEFTMOUSE, RIGHTMOUSE, EVT_TWEAK_L and
EVT_TWEAK_R events.
Other than that, there should be no functional changes.
This allows gizmo groups to store properties in the tool.
This makes sense for gizmo options which only control gizmo display and
don't control operator execution.
Unlike similar kinds of properties,
this isn't accessible via the gizmo-group-type instance.
For now the it's only stored in the workspace tool as can be done for
operator properties, so each instance doesn't have different settings
which would be confusing from a user perspective and complicate access
from the top-bar.
Later we could add gizmo-group properties if needed.
Displaying the labels tip immediately feels too intrusive,
make this work more like regular tooltips, displaying more quickly.
Tooltips can now uses multiple passes, each pass with it's own delay
for the next pass to show.
Add tool options to control how select operates (add/sub/set/and/xor).
Note: edit mode armature select still needs to support all options,
this is complicated by how it handles partial end-point selection.
