Summary:
Modernize `phutil_mapper.php` to prepare for killing `__init__.php`.
The current mapper is module-oriented and complex. Instead, make the mapper file-oriented and simpler.
We build a one-to-one cache of file content to symbols (built with `phutil_symbols.php`) and then write a simpler map. See some discussion in D2561.
Also make the script less messy/bad in general. It may be useful to compare this to phutil_mapper.php.
(Additionally, we now write versions into the library map and cache.)
NOTE: Nothing can read this new map right now, of course.
Test Plan: Ran "phutil_rebuild_map.php src/" in phabricator/ with --quiet, --drop-caches, etc. Verified cache file, cache behavior, and generated map output.
Reviewers: vrana, nh, btrahan
Reviewed By: vrana
CC: aran
Maniphest Tasks: T1103
Differential Revision: https://secure.phabricator.com/D2562
