Distribution EOLE

Merge no-current-message-1238-6

Author: exarkun
Reviewer: glyph
Fixes #1238
Fixes #1496
Fixes #1272
Fixes #1491
Fixes #1483
Fixes #1305
Fixes #1429

Automatic Athena event handler registration is fixed for all supported browsers
and is no longer document-sensitive (ie, it works inside tables now). Handler
tags are processed server-side when templates are loaded and rewritten to the
appropriate HTML before being served. Note that this means that only documents
which run through the document preprocessing mechanism will be able to use the
handler tag (so use docFactory!).

The XPath-specific implementation of node discovery in Athena's JavaScript runtime
module has been refactored, simplified, and now has well-defined (and unit tested)
error behavior.

Nit has gained a new assertion method, assertIn. Factoring of test collection has
also been improved, separating _TestMethod creation from discovery of the names
of the defined test methods.

The JavaScript classes which implement Mantissa's ScrollTable have been further
refactored, documented, and generally cleaned up. There is now an API for removing
rows, several existing asynchronous APIs now return Deferreds, and test coverage
has been further improved.

Quotient's inbox has been changed to use <athena:handler> in numerous places
to improve error handling. Many APIs have been changed to separate DOM concerns
from model concerns.

On the server side, the Quotient inbox no longer maintains state to track what
message the browser is currently displaying. All action methods now take an
argument specifying what message or group of messages to act on, removing the
possibility of the server acting on a message other than the one which the client
intended.

Much model logic has been factored out of the display classes which implement
the inbox. Overall documentation and test coverage has also been improved.