fixed a few typos in docstrings

Ignore-this: e869dfb4d0402e5adf46088b0c9c328b

darcs-hash:20090202114521-b2873-091db2b4a70f6077767eb560b7d7314673af54a0
don't catch PyPJUAError in Invitation.accept(). If it does raise the error that should be silented, catch those specific errors only

Ignore-this: e07faaccf588e382e3768cb9832eda94

darcs-hash:20090202114641-b2873-105443420b55a945b56acb8f39c3d159c844e4b2