Bump version to 0.5.0

Add doc about panic. Fixes #6.

Fix missing mutability of references. Simplify some tests.

Remove useless lifetime.

Fixes #4

Merge pull request #5 from JakubOnderka/master

Mark RawVec as Send

Make library compatible with stable Rust compiler.

 - All benchmarks removed for now. Will reintroduce later in
   ``benches`` directory which is handled by cargo.

 - Reimplement own version of ``RawVec``.

 - remove clippy dependency.

Fixes #1.

Release v0.2.0