rt: don't save and restore xmm/regs in __morestack.
Feed enum field offsets to type vistors.
Export adt::trans_get_discr abstractly to the type visitor.
When repr'ing an enum value, assert that it matched some variant.
Make the enum visit callback generator more readable
Make intrinsic::Opaque more opaque
Add debug info for boxes
Add debug info for vectors
Add debug info for bare_fn type
Prevent debug info generation of zero-span nodes

If a node has a (0, 0) span, it was not in the source, so debug symbols should not be generated for it.
Add debug info test for boxes
Add debug info test for vectors
add rustdoc comments with examples for the string versions of to_base64 and from_base64
rustpkg: Factor out tests; use a condition instead of returning an option

Pulled out tests into their own modules inside the files they test,
as per the draft style guidelines.

Started a new module, path_util, for utility functions to do with
paths and directories.

Changed default_dest_dir to use a condition and return Path
instead of Option<Path>.
Add comments for the implementations of from_base64 and to_base64 for .
fix index out of bounds error of x86_64 ABI
initial iterator object library
librusti: only use std::rl if stdin is connected to a tty.
move rustdoc comments so that they attach to the functions rather than the impl blocks.
Avoid excessive allocations and copies in iter::to_vec

The foldl based implementation allocates lots of unneeded vectors.
iter::map_to_vec is already optimized to avoid these.