hgweb: always run search when a query is entered (bc) This changes the behavior for queries which point at a revision directly, now the output is consistent to other cases: it results in only this matched revision shown, not the log starting with it. A new test checks this behaviour and fails for the old one.

hgweb: search() function supports direct pointing to revision This doesn't change the behavior, as queries directly pointing to revisions are not delegated to the search() function now.

hgweb: pass arguments which a function depends on explicitly in search This changes makes clearer which arguments can a function depend on. Now all the modified functions depend on the 'query' argument only, but future additions will change it.

hgweb: add dynamic search function selection, depending on the query This allows adding other specific search functions, in addition to current keyword search.