templater: separate function to create templater from map file (API) New frommapfile() function will make it clear when template aliases will be loaded. They should be applied to command arguments and templates in hgrc, but not to map files. Otherwise, our stock styles and web templates (i.e map-file templates) could be modified unintentionally. Future patches will add "aliases" argument to __init__(), but not to frommapfile().

templater: extract function that loads template map file Prepares for API change. See the next patch for details. 'map' variable is renamed to avoid shadowing map() function.

templater: demote "base" directory of map file to local variable It isn't referenced from other places.

notify: do not load style file if template is specified (BC) This patch makes sure that either "tmpl" or "mapfile" is exclusively set, which is the same behavior as common log-like templates and formatter outputs. See the previous patch for why.