Tutorial: comment on how mutability applies to boxes
src/librust/rust.rc: Fixes typo 'an executable' vs 'a executable'
Tutorial: fix typo
libstd: move bigint to dedicated num directory
libstd: add basic rational numbers
libstd: add basic complex numbers
libstd: make complex.rs XXX's into issues and FIXME's
refactor check_call_inner to have a better name and be readable
Move the replacement of bound regions out from `check_arguments` and into check_call / method_resolution
Rather than storing a list of ty::method per trait, store one ty::method
per method and list of def-ids per trait.
Compute a ty::method for methods that appear in impls as well
Pass around a pointer to the ty::method rather than the individual bits of info
Add a (currently unused) "transformed self type" pointer into ty::method
Refactor so that references to traits are not represented using a type with a
bare function store (which is not in fact a kind of value) but rather
ty::TraitRef.  Removes many uses of fail!() and other telltale signs of
type-semantic mismatch.

cc #4183 (not a fix, but related)
Fix various warnings, NOTEs, etc
Add comment explaining method visibility
rustc: Be careful about calls to fn types that contain nested errors
Link lifetimes of autoslice'd vectors (Issue #3184)

Fixes #5739.
Tutorial: spelling correction and move a failing test to an xfail-test marked code block.
Implement Clone for @ and @mut types.

The borrowck-borrow-from-expr-block test had to be updated. I'm not sure why
it compiled before since ~int was already clonable.