Fixed type signature of uninhabited method.

Added unit test to prevent similar mistakes from happening again. The
previous method was wrong because it dereferenced a pointer to a void type to
match on the result. No self pointer was needed, and the correct method
signature took the self value by value.
Update .gitignore
Issue #5967: Make rvalues mutable
Add explanatory comment to is_rvalue_or_immutable()
testsuite: Update and un-xfail unsafe-fn-autoderef
Better error reporting with renaming imports
Add test for resolution errors
Add span to some import resolution errors
Get span from import_directive
Fix ICE
Fix resolution tests
rustpkg: Implement URL-like package IDs

This patch implements package IDs like
github.com/catamorphism/test-pkg.

To support such package IDs, I changed the PkgId struct to contain
a LocalPath and a RemotePath field, where the RemotePath reflects
the actual URL and the LocalPath reflects the file name of the cached
copy. Right now, the only difference is that the local path doesn't
contain dashes, but this will change when we implement #6407.

Also, PkgIds now have a short_name field -- though the short name
can be derived from the LocalPath, I thought it was cleaner not to
call option::get() wantonly.
rustpkg: Tests for well-formed and ill-formed package IDs...

...and cleanup, making how we handle version numbers more rational
(specifically, not passing in a versioned name to rustc
with the -o flag), and removing unused code.
Rename vec::len(var) to var.len()
rusti: Ignore tests. Failing on i686. #6489
core: Fix leak in TLS. #6231
vim: swap operator is gone
vim: no more drop blocks
vim: `be` is still a reserved keyword
clone: clarify docstring