hgweb: drop useless **args from webutil.showtag() and showbookmark() Callers never pass excessive arguments to these functions.

hgweb: reuse graph node-related functions from templates The difference between templatekw.getgraphnode() and webutil.getgraphnode() is that the latter is not limited to 1 character.

templates: split getgraphnode() body into two functions getgraphnodecurrent() is checking if the node is currently checked out and getgraphnodesymbol() is checking properties that have more to do with the stored data and the DAG.