Working with coords move.
Remove old xyz Grid interface.
All tests (non-poly) pass with CoW. Perf sucks.
Co-locate refcount and data.
Remove vector from Grid.
Prepare merge.
Merge branch 'master' into cow
Added CoW as a compile-time option, enabled by default.
Add chunks spec to huge_map and any_iterator.
Factor out pather state caches.
Remove file too big for Github.
Update polymorphic API and tests to deal with PatherState.
Work around bugs in VS2013. All tests pass.
Compiles clean on Clang.