Fix karma.conf.js updating on Windows

Karma.conf.js may contain \r's when checked out on Windows. Cope with
these when updating the karma configuration file content.
Merge pull request #641 from peitschie/win-karma

Fix karma.conf.js updating on Windows
Add SessionBackend abstraction

hides away any assumptions about server class structures from the Editor class
Remove option to configure the member id in local edit mode
Merge pull request #624 from kossebau/sessionbackend

Reduce assumptions about backend in the editor
Ensure a caret doesn't receive any new events after destroy is invoked

Deleting the caret before calling ensures there is no way for any external
sources to get access to the soon-to-be destroyed caret.

As part of tracking this down, scheduled tasks will now throw an error
if an attempt is made to trigger the task (either delayed or immediate)
after the particular instance has been destroyed.

This then showed that functions bound to browser events swallow errors
quietly, so additional logging was added to the EventManager delegation
code to ensure errors generated when processing an event are logged.
Merge pull request #620 from peitschie/caret-destroy-fixup

Ensure a caret doesn't receive any new events after destroy is invoked
Wait with sending statereadychange until all items from the load queue have been handled.
Merge pull request #642 from vandenoever/canvasdone

Wait with sending statereadychange until all items from the load queue h...
Pass on expected sessionConstraints parameter to SessionView in viewer
plugin.
Merge pull request #643 from adityab/viewer-constraintfix

Fix viewer crash when initializing SessionView
Re-implement navigate-to-line-boundary cursor movement
Re-implement navigate-by-line cursor movement
Re-implement up/down movements caching the last caret X position

When navigating vi the up/down arrow keys, the user often wants to move
multiple lines in sequence (e.g., to visually place the caret in one of
the following lines). To stop the caret suddenly jumping to the left
side of the page when crossing an empty paragraph, the caret's X position
will be stored and re-used by subsequent up/down movement for up to 2s
after navigating by line.

Any other operations performed by the local user (e.g., cursor movement
to the left or right), or edit operations by collaborative users will
immediately clear the stored X position.