* 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 modifier tab.
* Fixed problems when no object was selected after delete.
* Added initial Armature, Bone, Curve and Font panels, by William Reynish (Billrey). Thanks!
* Small RNA changes
* Commit revision 20240 and 20268 from trunk. ("Mouse wheel zoom lost after rendering.")
