Blender Git Loki

Fix #34350: Maya Keyboard map preset problems

Two main things:

- Made a python operator for selection in a viewport
which will de-select everything if nothing is under
the mouse.

To do so needed to modify VIEW3D_OT_select, so invoke
sets mouse location which is later used by exec
function.

This way it's possible to select stuff from python
defined operator.

Not best-ever solution since ideally exec() shall not
do OpenGL stuff, but we've got this issue in some
other operators. We'll solve this later.

- Used a keymap from Gianmichele Mariani as a reference,
updated his keymap to latest changes in operators.

We shall match Maya keymap much better now, thanks
for the keymap dude!