Update pontarius-xmpp.cabal

Change in build-depends, package stm: version >= 2.4 is needed because of the use of the function 'cloneTChan'
Merge pull request #47 from MarcosPividori/patch-1

Update pontarius-xmpp.cabal
Parse version numbers properly; allow for >=1.1 and <2.0 versions

Fixes #50.
export streamState
lens updates