update compile-fail/map-types.rs to use hashmap
cat modernization (cleanup of a run-pass test)
remove old StdMap trait

this has been replaced by core::container::Map
rm commented out std::map code from json module

it was replaced by LinearMap
rename map -> oldmap and mark it as deprecated

LinearMap is quite a bit faster, and is fully owned/sendable without
requiring copies. The older std::map also doesn't use explicit self and
relies on mutable fields.
oldmap: get rid of the legacy contains_key method
oldmap: implement core::container::Container
oldmap: implement core::container::Mutable
oldmap: remove the legacy each_value method
oldmap: get rid of the legacy each_key method
oldmap: remove legacy each method
oldmap: start conversion to explicit self
oldmap: &K instead of K for the remove parameter
Moved all numeric modules in core into own directory

Reason: Better grouping of related modules, future-proving for a more extensive math library.
Added Round trait to core
Added ToStrRadix and FromStrRadix traits
Added char::from_digit(), char::is_digit_radix() and an argument check to char::to_digit().
Added some generic number functions to core::num

Also fixes previous commit not compiling due to not finding Option.
Added generic string <-> number conversion functions to core::num.

They unify the different implementations that exists in int-template.rs, uint-template.rs and float.rs into one pair of functions, which are also in principle usable for anything that implements the necessary numeric traits. Their usage is somewhat complex due to the large amount of arguments each one takes, but as they're not meant to be used directly that shouldn't be a problem.
Converted libcore/int-template.rs to the new string functions.

- Moved ToStr implementation of integers to int-template.rs.
- Marked the `str()` function as deprecated.
- Forwarded all conversion functions to `core::num::to_str_common()`
  and `core::num::from_str_common()`.
- Fixed most places in the codebase where `to_str()` is being used.
- Added int-template to_str and from_str overflow tests.