subscriptions 5.x-2.0-beta10

This is a ground-up rewrite of subscriptions.
This is a BETA release:

• Back up your database before installing!
• Do not install on a production site!
• Some features may be missing or incomplete or buggy...

The official release version is still subscriptions 5.x-1.9. However, it's known to be buggy and it's unmaintained. We are working hard on getting 2.0 out and you can help it by trying it out and reporting bugs.

All changes are by salvis.

Improve the digest template.
Tune other templates, split !type into !subs_type and !node_type.
Add some mail template documentation.
Update the German translation.
Tune node form positioning.
Convert node/nid into node/type when it's an update notification;
this implies merging comment notifications (as node/nid) only up to any subsequent update notification, so that that update notification can be converted (subsequent comments will be attached).
Fix some minor bugs.
Fix multiple taxonomies interfering with each other.
Improve explanatory strings, add missing German translations.
Clean up the conditional expression in subscriptions_ui_nodeapi().
Restore the conditional node form after overly restricting subscriptions_ui_nodeapi().
Remove the links from the node form item texts and document them in README.txt instead.
Restrict subscriptions_ui_nodeapi() to node/NID pages to avoid interfering with modules that render node content in different contexts.
Clean up: use $_GET['q'] to get the current path.
Implement optional Subscribe link, administrative interface.
Adjust weights on admin/settings/subscriptions.
Add comment to explain why we need to set the module's weight (no functional change).
Clean up the mess in subscriptions_content_mail_edit_submit().
Call check_markup() first to prepare text for drupal_html_to_text().
Move subscriptions_mail_send() to private namespace to avoid conflicts.