nanorand v0.7.0

Changelog (from 0.6.1)

• Reworked the API heavily
  • The Rng trait now uses const generics for output length, rather than an associated type
  • Added Rng::fill_bytes, and reworked RandomGen implementations to use it.
  • Rng::reseed was move into the new SeedableRng trait.
  • All RNGs now have a Debug implementation
• Completely reworked the C API.
• Added BufferedRng, a wrapper around an Rng that buffers output, and will use buffered output rather than wasting perfectly good random bytes.
• Set MSRV at Rust 1.56.0
  • Rust 2021 is used.
• Removed nanorand-py (not like anyone used it anyways)
• Fixed signed integer generation!
• Clarified in the docs that RandomRange will panic with an invalid range.