* Fix buttons jumping around when resizing and zoom. Part of this was
adding a tiny a 0.001f offset in UI_view2d_view_ortho, otherwise the
rounding is unpredictable (used to be 0.375f, but that was disabled).
* Fix various issues with zooming, panning panels. V2D_LOCKOFS_X/Y is
now taken into account in more places in the view2d code, to avoid
zooming into the center or panning out of the view.
* Remove "Free" align mode in buttons window (it's not really useful).
* View3D/Graph/Image editors now use the same PanelType system as the
buttons window, means some deprecated panel code could be removed.
* Some small visual tweaks for panels.
* View 2D Reset operator (Home key), to reset zoom and panning for panels.
* Added argument to set number buttons as sliders (slider=True for itemR).
* Ignore labels for button alignment (doesn't look right).
* Fix some use of context.main in py scripts, should get data from active
object instead.
* Fix autotexspace -> auto_texspace in py script.
* Added new Buttons Tab "Bone" for Armature objects.
* Validation of buttons selection, when object selection is changed.
* added missing notifier for camera type and small layout change to the panel.
* more shading color changes for menu and checkbox.
* Buttons are now created first, and after that the layout is computed.
This means the layout engine now works at button level, and makes it
easier to write templates. Otherwise you had to store all info and
create the buttons later.
* Added interface_templates.c as a separate file to put templates in.
These can contain regular buttons, and can be put in a Free layout,
which means you can specify manual coordinates, but still get nested
correct inside other layouts.
* API was changed to allow better nesting. Previously items were added
in the last added layout specifier, i.e. one level up in the layout
hierarchy. This doesn't work well in always, so now when creating things
like rows or columns it always returns a layout which you have to add
the items in. All py scripts were updated to follow this.
* Computing the layout now goes in two passes, first estimating the
required width/height of all nested layouts, and then in the second
pass using the results of that to decide on the actual locations.
* Enum and array buttons now follow the direction of the layout, i.e.
they are vertical or horizontal depending if they are in a column or row.
* Color properties now get a color picker, and only get the additional
RGB sliders with Expand=True.
* File/directory string properties now get a button next to them for
opening the file browse, though this is not implemented yet.
* Layout items can now be aligned, set align=True when creating a column,
row, etc.
* Buttons now get a minimum width of one icon (avoids squashing icon
buttons).
* Moved some more space variables into Style.
* Split the buttons_data.py into separate files, this makes it easier to maintain them.
Notes: Added an extra modifier file, because modifiers are for different object types.
* Added basic lamp buttons and Sun/Sky settings.
As the camera buttons they only work for the default light object for now.
* Some minor code cleanup
