Add tweetmarker support

[simonszu]

Tweetmarker is a service to save the read-state of ones timeline across multiple devices, so that one can continue reading twitter on the phone after he left his computer.
The developer of tweetmarker currently charges $25/month per app, but he said that developers of open source apps can contact him to find a solution for this problem.

Currently no twitter clients for linux have tweetmarker support, so implementing tweetmarker support in Surfbird would cause some kind of push, since the demand for tweetmarker support on the Linux desktop is quite high.

[pixeldesu]

Sounds like a nice idea, definitely something to consider implementing!

I will need to keep that somewhat back for now as I'm still in the rewrite phase and want to get basic features working again.