exchange: only push the set of marker relevant to want we push
We now compute all markers relevant to pushed set. And just send just those one.
So you are no longer pushing markers that point to changeset your are not
pushing. See the in line comment for details about what "relevant" is.
Multiple nice output have been added in the process.
doc generated with sphinx. tutorial exported using sphinxedhg
http://hg.piranha.org.ua/sphinxedhg/