color: move 'debugcolor' into the 'debugcommands' modules
This is the last bits we needed to move out of the extensions. 'hgext/color.py'
now only contains logic to changes the default color behavior to 'auto'.
However, more cleanups are on the way and we need to document the new config
directly in core.
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username
foobar
#endif