Lift Framework 3.0-M6

This release features a good bit of cleanup from the previous one. It's been a busy
few months for the committers so the work is mostly in targeted improvements and
bug fixes:

Improvements

• (#1706) Thanks to @chriswebster, an up to 90% performance increase in JSON
  serialization for lift-json!
• (#1693) ParamFailure now behaves more correctly with ~>. That operator, when
  used on a Failure, returns a ParamFailure with the passed parameter, while
  preserving the rest of the original Failure's information. Before, invoking ~> with
  a parameter on a ParamFailure would replace the existing parameter with the new
  one, thus losing the previous parameter altogether. Now, we produce a copy of the
  ParamFailure with the new parameter, but we chain the previous ParamFailure
  to it so that it the original parameter is still accessible.
• (#1698) Lift 3 sessions allow an actor proxy for client code to be created via
  serverActorForClient. This release includes some new setup configuration
  when creating those actors, like providing setup and teardown functions as well
  as ways to convert from application messages into client JS content.
• (#1701) There is now a LiftRules.attributeForRemovedEventAttributes. When
  Lift strips event-related attributes (e.g. onclick, onsubmit, etc), if this rule is
  set to a String, it will tag the element whose event attributes were removed
  with the attributes that were removed. For example, setting it to Some("data-lift-removed-attributes")
  might result in a data-lift-removed-attributes="onclick onmouseover" attribute
  in your HTML if that element had its click and mouseover event handlers moved
  into page-specific JS. This allows you to make styling decisions based on these
  attributes, if you want to. See the rule documentation for more.
• (#1705) Until now, jsonCall would fail silently on both client and server if the
  submitted data from the client wasn't valid JSON. Now, it will log (at an ERROR
  log level) on the server if invalid JSON is sent. Whether this log info will be printed
  or not is configurable using usual logger configuration.
• (#1709) You can now register to find out when a function owner no longer has
  available functions bound in a session. Function owners typically (though not always)
  correspond to server-side functions bound or a page rendering (e.g., form fields).
  These usually expire ~2 minutes after the user is no longer on the page, but until
  now there was no way to find out that a given page was no longer “in scope”. In
  certain cases, that could be interesting to clean up page-related temporary assets
  or resource allocations. We now provide LiftSession.onFunctionOwnersRemoved,
  which can be set during application startup so that any new sessions can register
  those listeners. @andreak posted an excellent example of how they are using this
  on the mailing list.

Bug Fixes

• (#1694) When generating post-page JavaScript (mostly used by Wiring), there
  were some cases where null pointer exceptions could be thrown. These should
  be gone.
• (#1692) When binding onclick to an element that had an href, the new code
  that extracts event handlers into page-specific JS was failing to bind the click
  handler. This is now fixed, as is a related bug where elements that didn't need
  handlers still had a random id assigned to them.
• (#1677) When sending messages to comet actors before they are created (via
  LiftSession.sendCometActorMessage), they would arrive in reverse order.
  This is now fixed, and the first message sent using sendCometActorMessage
  arrives first.
• (#1703) When we moved away from bind, the CSS bindings in ProtoUser
  that checked password changes were incorrect, in that they never saw the
  user having submitted two versions of the same password. This is now fixed,
  and the change password stuff provided by ProtoUser is now correct.