Growl 2.0 Beta 20

* improved History tab: added detail view and filtering capability
* added better proxy support, including support for custom authentication (though still manually configured)
* changed the Growl.CoreLibrary and Growl.Connector assemblies to compile for AnyCPU instead of x86, so they should work in 64-bit apps now
* updated the CallbackContext class' interface to be more intuitive and easier to use
* added the ability to specify relative icon paths in growlnotify
* added /silent switch to growlnotify to suppress all output
* removed /cc switch from growlnotify (since it is not used)
* fixed a bug that caused Notification-Callback-Target headers to be ignored
* fixed a bug that incorrectly required setting Notification-Callback-Context and Notification-Callback-Context-Type for url callbacks
* fixed a bug that caused Subscriptions to generate multiple entries in the origin machine's Forward list
* fixed a bug that could cause subscription passwords to show up in the Password Manager
* fixed a bug that could cause passwords to become 'stuck' in the Password Manager
* fixed a bug that could crash Growl if a url-based image was not available
* fixed a bug in the Outlook Add-in that wouldnt show a notification if the email subject was empty
* fixed a bug in the Outlook Add-in that didnt notify on new meeting requests
* updated Google Voice Greasemonkey script to show full SMS or Voicemail message text