Properly mark layers as dirty on fill()
Fix crash on layer stack painting
Dualcolorbutton visual improvements
Restored brush outline drawing
various fixes/tweaks
Layerstack: tolerate zero layers
Implemented lag simulator for loopback server
naming style change
Prepare for canvasitem geometry change on resize

Currently actual canvas resizing is not implemented,
but this is needed for the initial resize when the canvas
is first created.
Preview strokes work again
disable preview strokes in local server mode
zoom with ctrl+mouse wheel
Proper coordinate encoding
use qWarning() on unrecognized command