Bugfix: Activation of disposed tabs

  Derived from https://github.com/echo3/echo3extras/pull/2

  In some situations on adding/removing tabs via server side
  API, the client logic tried to modify tabs which are already
  disposed. Minor null-check workarounds this. Not sure if this
  is already the root problem.
Extras.CalendarSelect fixes for IE 9
  Provided by ScoPi http://echo.nextapp.com/site/node/6715
  This commit propably needs a review as stated in the message:

  So admittedly this may not be the most appropriate way to fix
  the underlying issue, but the bug we've seen in IE 9 when using
  the Extras.CalendarSelect control is addressed by this.
  The symptoms of the bug were two-fold:

	1. The month select field could not be used. It didn't
	   appear to respond to mouse clicks and open.
	2. You had to double-click on a particular day in a month
	   grid to select it as opposed to one click.

  The reason for the above problems appears to have been related
  to a runaway recursive call that only affected IE 9. The below
  fixes this issue specifically for Internet Explorer 9, and
  everything still appears to work fine.
Configurable build properties via unversioned "custom-ant.properties".
Fix ant-task  "release" due to missing empty dir.
Align project and files to Maven-like naming style.
Provide -sources.jar bundles.
Merge branch 'hotfix/ie9-calendarselect'
Merge branch 'master' of github.com:echo3/echo3extras