Add intermediate points to make quick free drawings smoother.
Do not redisplay the area at this step (crashes).
Use device.get_coords rather than global.get_pointer because the later return rounded (floor) values.
Fix#45.
* Import palettes from a .gpl file (one palette for each column).
* Add possibility to use more than 9 palettes.
* Color display names support.
* color.toJSON for svg and drawing saves, color.toString for display.
use `PangoCairo.show_layout_line` instead of `PangoCairo.show_layout`. It is equivalent.
show_layout (doc): "The top-left corner of the PangoLayout will be drawn at the current point of the cairo context."
show_layout_line (doc): "The origin of the glyphs (the left edge of the line) will be drawn at the current point of the cairo context."
So it is no longer necessary to query `layout.get_baseline()`.
* Group "transform" attributes.
* Round "transform" attribute values.
* Remove unused stroke attributes.
* Add an "eraser" class attribute to let user retrieve the element role.
* Pass Clutter color and Pango fontDescription objects to elements, not strings.
* Do not use the color format '#rrggbbaa' in svg since it is not supported in GNOME 3.24.
* It is no longer required to clamp the setting value in area.js.
* Add a "range" property, completed with another 'step' property, to PixelSpinButton in order to directly initiate the lower and upper values of the adjustment from the relevant setting range.
* Not related: fix an inversion between Pango and Cairo in element.js.
abakkk