std: Replace num::IntConvertible with {To,From}Primitive
syntax: Add #[deriving(FromPrimitive)] syntax extension

Right now this only works for c-style enums.
syntax: swap from .span_fatal to .span_err in #[deriving(FromPrimitive)]
test: add compile-fail test for #[deriving(FromPrimitive)]
std: Swap {To,From}Primitive to use the 64bit as the unimplemented version

One downside with this current implementation is that since BigInt's
default is now 64 bit, we can convert larger BigInt's to a primitive,
however the current implementation on 32 bit architectures does not
take advantage of this fact.
extra: Add ToBigInt and ToBigUint traits
auto merge of #9718 : alexcrichton/rust/snapshots, r=sanxiyn

Now that #9662 is merged, we should be much more easily bootstrappable on
windows now.
auto merge of #9722 : alexcrichton/rust/less-mem, r=sanxiyn

According to http://huonw.github.io/isrustfastyet/mem/#012f909, the "const
marking" pass generates about 400MB of extra memory during compilation. It
appears that this is due to two different factors:

    1. There is a `ccache` map in the ty::ctxt which is only ever used in this
       pass, so this commit moves the map out of the ty::ctxt struct and into
       just this pass's visitor. This turned out to not benefit that much in
       memory (as indicated by http://i.imgur.com/Eo4iOzK.png), but it's helpful
       to do nonetheless.

    2. During const_eval, there are a lot of lookups into decoding inlined items
       from external crates. There is no caching involved here, so the same
       static or variant could be re-translated many times. After adding
       separate caches for variants and statics, the memory peak of compiling
       rustc decreased by 200MB (as evident by http://i.imgur.com/ULAUMtq.png)

The culmination of this is basically a slight reorganization of a caching map
for the const_eval pass along with a 200MB decrease in peak memory usage when
compiling librustc.
Fix minor typo in std::str module docs
Fixed another minor typo in std::str docs
auto merge of #9726 : Valloric/rust/typo_fix, r=alexcrichton
auto merge of #9727 : Valloric/rust/doc-fixes, r=catamorphism
Fix thread safety issues in dynamic_lib

The root issue is that dlerror isn't reentrant or even thread safe.

The Windows code isn't affected since errno is thread-local on Windows
and it's running in an atomically block to ensure there isn't a green
thread context switch.

Closes #8156
Make a task name use a `SendStr`, allowing for either
static or owned strings
Implemented `IntoSendStr` on `SendStr` to allow naming a
task with a `SendStr` directly
auto merge of #9731 : Kimundi/rust/SendStrTaskName, r=alexcrichton

This resolves a FIXME in `std::rt::task`.
std: check bounds for ints/uints in {To,From}Primitive
extra: Don't truncate {u64,i64} when converting to BigInts
std: fix some warnings
std: ToPrimitive's default impls should use `.to_*()`

This allows the default methods to be properly range checked.