Merge tag 'v0.20.3' into develop

0.20.3
Documented an additional limitation.
Added a missing PHONY.
More TODO.
Support for tunnel creation.
Increased the screen size.
Optimize module fetching in kitchen-sink.
Start the server in a separate thread.
Added a serializer.

The serializer is needed to avoid IE-specific issues.
Sort attributes when creating elements.

Sort the attributes so that we have a stable order across browsers.
Improved the namespace detection code.
Fixed a bug in the caret position logic.

The code that cleans up the caret when a placeholder is removed and
contains the caret would prematurely terminate a text undo group. This
could cause a crash during undo operations. It has been fixed.
Properly clean the tunnel files.
Version bump.
Merge branch 'release/0.20.4'