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.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.