* 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.