New byte buffer This new byte buffer implements a simple dynamic buffer. It aims to * Provide a clean API. * Convince the compiler to generate good code. In particular it tries to avoid unnecessary loads and stores which are otherwise generated due to the C aliasing rules. This is done using the STATIC_ASSUME(X) macro, which declare !X as unreachable. * Have the fast path (when the buffer has enough space) completely inlined to allow the compiler to batch single byte writes to the buffer into larger stores.