namespaces: add method to return a list of nodes for a given name
This is a helpful method that some extensions can make use of (e.g. for custom
revsets); currently not used in core.
test --time
$ hg --time help -q help 2>&1 | grep time > /dev/null
$ hg init a
$ cd a
#if lsprof
test --profile
$ hg --profile st 2>../out
$ grep CallCount ../out > /dev/null || cat ../out
$ hg --profile --config profiling.output=../out st
$ grep CallCount ../out > /dev/null || cat ../out
$ hg --profile --config profiling.format=text st 2>../out
$ grep CallCount ../out > /dev/null || cat ../out
$ echo "[profiling]" >> $HGRCPATH
$ echo "format=kcachegrind" >> $HGRCPATH
$ hg --profile st 2>../out
$ grep 'events: Ticks' ../out > /dev/null || cat ../out
$ hg --profile --config profiling.output=../out st
$ grep 'events: Ticks' ../out > /dev/null || cat ../out
#endif
$ cd ..