Replace ChaCha20Poly1305 implementation
Replace ChaCha20Poly1305 implementation

Improve AEAD speed with slightly faster poly1305 implementation.
Avoid memory allocations whenever possible. (AEAD)
But currently missing AVX2 support.

BenchmarkSeal64B-8     1561 ns/op       40.97 MB/s
BenchmarkSeal1K-8      5570 ns/op      183.82 MB/s
BenchmarkSeal64K-8     161271 ns/op    406.37 MB/s
BenchmarkOpen64B-8     1747 ns/op       45.79 MB/s
BenchmarkOpen1K-8      5741 ns/op      181.14 MB/s
BenchmarkOpen64K-8     157116 ns/op    417.22 MB/s

lucas-clemente/quic-go,konnykonny50/quic-go,lucas-clemente/quic-go,konnykonny50/quic-go