telephone-event codec ignored because \w was too strict - for #16
format function support was bad when the grammar did not work on a push attribute
a=rtcp grammar using new conditional stuff - fixes #16
convention is test for any not existing (so follow, even though it is only one)
add some tests for #16 - rtcp grammar and telephone-event
history for 0.5.1 - bugfix release
0.5.1