notifications 5.x-1.0-rc2

Multiple bug fixes and some new features:
- Fixed notices and code readability, by Zen, #310598
- Fixed concatenationsyntax error, by Zen, #310594
- Implemented: configurable events to trigger or not notification, #255402
- Moved developer documentation to online handbook, http://drupal.org/node/253102
- Spin off notifications_mail2web to it's own package, http://drupal.org/project/mail2web
- Fixed multiple strings across all modules, by rastatt, #290063
- Fixed typo in notifications_autosubscribe form text
- Added inline documentation about the messaging/notifications API
- Removed obsoleted 'pull' operation in notifications_messaging()
- Better query building and more flexibility in notifications_user_get_subscriptions()