Added basic drushsubtree command.

  drush subtree <command> <name> [<args>,...]

	modified:   drushsubtree.drush.inc
Fixed minor typos and logging/printing bugs.

	modified:   drushsubtree.drush.inc
	modified:   drushsubtree.subtreecommander.class.inc
Changed command names to simplify interface.

  Fixed minor bug with _drushsubtree_get_name(), accidentally changed previously
  during other broad find/replace function name update.

	modified:   drushsubtree.drush.inc
Changed _buildmanager_get_config() -> buildmanager_get_config().

	modified:   buildmanager.drush.inc
Updated options and help text for clarity and consistency.

	modified:   drushsubtree.drush.inc