Blender Git Loki

Minor adjustments to the cage transform widget and sequencer operator.

* Bigger scale handler for widget.
* Operator has description on area
* Cancelling resets position.

Merge branch 'master' into wiggly-widgets

Conflicts:
source/blender/makesrna/intern/rna_space.c
source/blender/windowmanager/WM_api.h
source/blender/windowmanager/intern/wm_event_system.c

Sequencer operator that uses widgets and controls the placement of the
backdrop is now functional.

The widget could communicate with the sequencer properties directly, but
here we set it to control the operator properties as a demonstration.

After some minor stress testing, time to give this to gooseberry team.

Fix some registration issues, also add scale property for sequencer
backdrop widget.

Something draws now in sequencer when we register the widget for the
operator.

Yet more refactoring:

Areas support more than one widgetmap - will be useful to partition area
in different transform regions like data, pixel, 3D (will be done in a
separate refactor).

Also get rid of the context widget hack in favour of adding the
widgetmap handler to the operator handler itself, so handling will
be unified when the widget controls a property or spawns an operator

Privatize registration function for individual widgets.
Handle events for widgetmap first when and pass to operator when
operator is active.

This is still a pretty confusing design, working on a simpler one now.

Create sequencer widget handlers

Add back idnames to the widgetmaps, we could well need to define both
for different transform areas.

Big refactor commit.

* Minor cleanup - propname does not need to be stored anymore.
* Code to support modal widgetmap registration for operators - still
untested, but will be tested soon on sequencer cage widget
* Widgets take parameters to initialize property slots that are used for
feedback or control.
Cage now uses this to feed offset/scale to different properties.
* Initialize common properties during widget registration.

Code for runtime registration of widgets that should make it possible to
remove and add widgetgroup types from the system.

Start operator that will control sequencer backdrop. Architecture here
still needs a little work so good compatibility with Add-ons can be
ensured.

Make resizer widgets smaller, express them in pixels.

Clamp during rectangle interaction to make sure widget stays big enough
to interact with (also handles negative case). 15 pixels threshold was
chosen.

Correct backdrop fit operator for compositor.

Scale handlers for the rectangle transform working

Initial Python API for Widgets

Note this is only the initial Python API structure & isn't usable in its current state.

Work by Psy-fi & myself.

minor corrections to last commit

Widget API: remove unused identifier member

also comment some of the code.

Add facemaps panel to the supported cycles panels

Add back an extra paramater to the intersection function to determine
the highlighted part of the widget.