allocator_api 0.4.0

This is a copy of the unstable allocator_api (https://github.com/rust-lang/rust/issues/32838) and of parts of the unstable alloc feature. Usable with stable rust, but requires 1.26.
Documentation
Builds

allocator_api's sandbox limits

All the builds on docs.rs are executed inside a sandbox with limited resources. The limits for this crate are the following:

Available RAM 6 GB
Maximum rustdoc execution time 15 minutes
Maximum size of a build log 100 kB
Network access blocked
Maximum number of build targets 10

If a build fails because it hit one of those limits please open an issue to get them increased.