Patch against strongarm

Hi there,

In lack of an existing patch I created one. It's build against the latest 7.x-2.x-dev version of Strongarm.
I also made some small additional changes:

• Replaced the usage of theme("table_select_header_cell") - it's deprecated for D7.
• Fixed issue in variable_features_revert() - replaced $vars['name']->value by $vars[$name]->value.

Fixed a typo in das-peter's patch and posted it to #1094598: Performance issues from strongarm_init().

Thank you both for keeping this alive :)
@Pisco: As promised I digged into the installation issue. I think I got it - at least it works out on all our stages.

The patch is again for 7.x-2.x-dev and includes:

• All the work done by stijndm
• #1190936: Drush integration to facilitate non-Features-based strongarming provided by Grayside
• #1240308: Features revert code has an error provided by catch & Pisco

To make it easier to update the patch for 6.x I've attached the diff between the both patches.
Changes:

• Changed variable value comparison from != to !== needed to ensure arrays are really equal.
• Changed condition in variable_features_rebuild to this
  if (isset($vars[$name]->in_code_only) || (drupal_installation_attempted() && $vars[$name]->export_type & EXPORT_IN_CODE)) {
  This allows that the variables are set during the installation.
  (Maybe we don't event need isset($default->in_code_only) now - but I'm not sure about that.)