Improve extdiff configuration.
In addition to the old cmd.foo, opts.foo hgrc entries, allow a more simple
alias = command [opts]... form. For example:
[extdiff]
cdiff = colordiff -uprN
#!/bin/sh
# test parents command
hg init repo
cd repo
echo % no working directory
hg parents
echo a > a
echo b > b
hg ci -Amab -d '0 0'
echo a >> a
hg ci -Ama -d '1 0'
echo b >> b
hg ci -Amb -d '2 0'
echo % hg parents
hg parents
echo % hg parents a
hg parents a
echo % hg parents -r 2
hg parents -r 2
echo % hg parents -r 2 a
hg parents -r 2 a
echo % hg parents -r 2 ../a
hg parents -r 2 ../a
echo '% cd dir; hg parents -r 2 ../a'
mkdir dir
cd dir
hg parents -r 2 ../a
echo '% hg parents -r 2 path:a'
hg parents -r 2 path:a
echo '% hg parents -r 2 glob:a'
cd ..
hg parents -r 2 glob:a
true