user preferences API
Add a hover button to hide images.

This still has a scroll-to-bottom bug.

Fixes #77.
Preferences hooked up to server.

* Alert sound preference functional
* Enter/shift-enter preference functional
* Image auto-hide not implemented yet, pending that feature being merged.

Fixes #78.
Merge pull request #78 from bkad/preferences

User preferences
refactor currentChannel into a global variable
refactor messagehub into a singleton
change ChannelUsers to be a singleton
make ChatControls into a singleton
refactor global name of channelViewCollection
rename ChannelUsers to just Users
Add an image link to hidden images.
fix merge conflicts
Hook up the auto-hide images preference.
Fix up list styles.

Fixes #72.
Remove unused style.
Hack to work around disappearing bottom margin.

This is an issue whenever position: absolute is used inside messages.

This should become unnecessary in a future Chrome release that apparently
fixes a Webkit bug.
bugfix: new channels don't render properly
special case punctuation when matching channel names and user mentions

fixes #49
scroll to bottom when joining a new channel
add gravatar FAQ