Protected sipsimple.clients.ui from errors from eventlet RLock

Ignore-this: e3038c8aba02f7fc3b8f04665c6b31c9

darcs-hash:20090908085007-1e3d8-1cea039bc9b4ce6e6c31ad50140fa1a5426f55b3
Added handling in Invitation for timeouts to reINVITEs

Ignore-this: f712402c4ed695f1e172a6db29d4ef90

darcs-hash:20090908085149-1e3d8-def7132c2b7b34143726f6c1bde44adf16512627