That is, for example, import x::y::x, which defines a local x,
and thus wouldn't be able to find x::y anymore.

Closes issue #624

Closes issue #631

Removes ty::strip_boxes entirely, since unboxing is now more complicated
anyway.

trans::trans_lval will now autobind if the given expression was the
name of a generic functions. Those callees (trans_call and trans_bind)
that are interested in the generics information call trans_lval_gen
now.

Closes issue #639

The first is that the memory_region destructor would complain there is
still an outstanding allocation. This is because circular_buffer from
rust_chan wasn't refing its task, so the task was being destructed too
soon.

The second was where the program could deadlock while joining a
task. The target task would die in the time between checking whether
the task should block and then actually blocking. The fix is to use
the target task's lock.

feasible to turn it on and run rustc.

make it harder to use the wrong one.

Ports and channels have been moved to the kernel pool, since they've
been known to outlive their associated task. This probably isn't the
right thing to do, the life cycle needs fixed instead.

Some refactorying in memory_region.cpp. Added a helper function to
increment and decrement the allocation counter. This makes it easier
to switch between atomic and non-atomic increments. Using atomic
increments for now, although this still does not fix the problem.

Previously, we were creating both a normal vtable entry and a
forwarding function for overriding methods, when they should have just
gotten a vtable entry.  This patch fixes that.

Not sure why they were implicit since their dependencies only work for rustc

New snapshots also include rt and rustllvm

Doesn't seem like this has been required for a while. I don't know enough
about the windows build to try to touch that.

Once we've updated the snapshots to include them we can remove these rules

Allocate ivecs out of the kernel pool

All users were constructing the context the same way.

Rename metadata::tags to metadata::common. Move some utility functions from
metadata::encoder to metadata::common.