Regularly poll the list of blocked accounts and filter search and
subscription results by this list.
This is a very close copy of the friends list handling.

Only the block list for the current account was read.  This has been
changed to querying all accounts for their block lists.  Every block
applies globally, e.g. it filters results from _any_ account.

Seems reasonable to me because I use blocks to remove unwanted results
(spammers etc.) and these results don't become wanted just because
another account stumbles upon them.

Gedge found out that Twitter does not honor the page attribute to the
blocks/blocking method which makes us download the same block list 10
times for every account.  Talk about The Big Freeze on startup...

The existing twitter_friends_poll setting is used for both friends and blocks.

This should fix a case-related bug that seems to pop up sometime
(don't know why, though).  Account names are case insensitive so
using all lowercase can't hurt.

…h_block

As Gedge pointed out, $settings{blocks_poll} does not exist.  Use
$settings{friends_poll} instead, as documented in html/using.html.

I don't see much sense in polling the friends and blocks lists at
different intervals, so just use the same setting for both lists for
now.