Upgrades the edition, with changes primarily performed by
`cargo fix --edition`.
In order to keep the changes to a minimum, this doesn't include
automated idiom fixes (i.e. `cargo fix --edition-idioms`).
This is needed to unblock the edition upgrade for the RSA crate:
https://github.com/RustCrypto/RSA/pull/135
* no_std support
* Use integer log2 when possible to estimate allocations
* Remove std features from a few dependencies
* Use libm for missing funcs in nostd environment
* Use autocfg to detect presence of i128
* Better CI test for nostd environment
* Move benchmark to a separate crate
* Make the tests pass in no_std builds
* Use thumbv7m target for nostd build test
* Add documentation about the no-std compatibility
* Make zeroize and prime features no_std-compatible
* Test each feature in nostd context
* Fix mac test to work in no_std environment
* Avoid using thread_rng in nostd tests
* Fix prime tests in nostd mode
* Fix all warnings and errors
* Only test nostd builds on nightly on travis
* Travis: Only do nostd builds on nightly
The test modules were getting huge, and some of its functions were
actually a huge amount of code due to macros, causing tests to take a
long time just to compile. They are now separated into a few different
tests, and the scalar macros especially are now expanded more sparingly
in just a few `check()` functions.
Test compile times for me went from about 25 seconds to 1.5s in debug
mode, and from 300 seconds (!) to about 8s in release mode.
