String freeze: Better throttle description and help text for Blocks module

- So is there no value in linking to the Throttle config page?
- While we are here, why not break up this long help text to t()'s per paragraph, as used elsewhere? (And as it is much easier for translators).

Note that there is an older issue for block module help text, at http://drupal.org/node/189865. But, it has no patch so I'd say just close that one as a duplicate if you want to continue here.

I haven't looked at this help text in detail, but this may also be an opportunity to add text addressing the new drag-and-drop ordering functionality for the blocks page.

I just happened to notice this existing line at the bottom of the patch:

       return '<p>'. t('Here you can create a new block. Once you have created this block you must make it active and give it a place on the page using <a href="@overview">blocks</a>. The description is used in the "block" column on the <a href="@overview">blocks</a> page.', array('@overview' => url('admin/build/block'))) .'</p>';

When we say "make it active and give it a place on the page", this does mean enable and position, right? It may be out of scope here, but this line looks like it could use some tweaking.

- Thanks for breaking the big stuff up :) Although our code style requires that dots stick to the literal strings, so eg. '<li>'. instead of '<li>' .
- position it on the page using <a href="@overview">blocks</a>? Using blocks?

No patch attached. :(

I started putting the drag-and-drop stuff in per #4, and wound up with a wholescale rewrite.

The attached patch:
* reworks the main help text, plus the text headers over the main block pages.
* It does handle the drag-and-drop stuff, though not every eventuality (like non-js browsers, etc.)
* I put the throttle-specific help on the admin/build/block page inside a conditional so that it only appears if throttle.module exists.
* This patch uses gaele's work from previous patches to split the help text into more manageable strings for translation.

This is a major rewrite, so I'm going to expand the scope of this issue to cover the help text as well.

Added a note about remembering to click Save blocks after reordering block items.

Reading it through, it looks like a huge improvement so I committed this one. I am not sure how non-JS browsers can be accomodated here, but if you have good ideas, feel free to reopen the issue. The "when allowed by an administrator, specific blocks.." part also looked a bit strange, but I tried to come up with better wording myself, and was unable to. So feel free to submit a small improvement for that too in an issue follow up on this same issue, if you have better ideas. Thanks.