Combine consecutive comments / synopsis to blocks

[mkoskim]

Consecutive comments and synopsis paragraphs could be combined to one block like editors do bulleted / numbered lists.

Benefit: Comment & synopsis blocks have one entry in the index. This could encourage writing longer synopses.

Modifications

First, of course, we need editor to combine blocks.

Second, we need to change file format:

Now:

<comment>...</comment>
<comment>...</comment>

Change to:

<comment>
  <p>...</p>
  <p>...</p>
</comment>

Same for synopses.