2. remove extra algorithms

no impact to existing hook_match implementations.

2. modify the interface for hook_match()
3. implement the default hook_args_form_handler()

2. automatically enable the 'async' module

take into account the effects of comments. basically, we consider comments as a part of node itself.

there is a bug for the sake of performance. refer to pivots_async.module for details.

2. magicword can be set to null (match 'title' only).

2. add pivots_hook_block_title().

async algorithms are now using the the serailzed arguments to save start_mark, rather than system varibles.