Get rid of errors in log when opening chatsrooms.

The errors I'm talking about are:
[WARNING] http://localhost:8080/dojo-release-1.9.3-src/dojo/parser.js:899 dojo/parser::parse() error
[WARNING] http://localhost:8080/dojo-release-1.9.3-src/dijit/layout/ContentPane.js:586 Error parsing in _ContentSetter#undefined
[WARNING] http://localhost:8080/dojo-release-1.9.3-src/dijit/layout/ContentPane.js:443 Error undefined running custom onLoad code: This deferred has already been resolved
Avoid content overflowing in mainContainer.
Avoid overflow in ChatRoom's mainContainer.
Fix some layout issues with chat.
Prevent overflow in topPane.

The layout functionality of ContentPane was kicking in and making the
TabContainer too large.
Add border-style declarations to fix margin box.

Without border-style (i.e. with border-style: none) webkit (and by
extension dojo) reports the margin box of elements ignoring the border,
even when when border-image is set.
Remove box-sizing: border-box from playerListPane.
Add code to filter js console messages (commented).
Update pr-downloader to 0.7-146-g620bd64.

The previous version was 0.7-66-ge9d6a9d.
The new version shows progress for engine downloads.
Mac pr-downloader not affected.
Show engine download progress.
Don't let download bars strech too wide.

They could cover the manual download button making it impossible to press.
Don't rename the start button to Spectate in SP.
Shrink bottom pane properly if room gets closed.
Strip pr-downloader binaries.
Support leading zeroes in chat color codes.
Don't steal focus on double click.

Widgets using the _HasDropDown mixin steal focus due to a WebKit bug,
see #9.
Implement startbox split and corners in hosted/sp battle.
Restore data-dojo-attach-point="boxesDropDown".

It's needed for the focus stealing preventing hack to run.
Ignore repo update progress in pr-downloader.

This prevents the progress bar jumping to 100% and back.
Merge branch 'master' into threaded_unitsync