More granular number of foum topic in blocks

Currently the two forum topic blocks share a number of topics in block setting. This is a bit confusing since configuring one block should not affect another block.

To finish this properly we should have a db update to copy the value of 'forum_block_num' to 'forum_block_num_0' and 'forum_block_num_1' and then delete 'forum_block_num'.

Fixed some indentation as well.