Categorise tests
Fix cabal with new test files
Add test case for simple Buffer functionality
Add Data.Buffer module

Implements Buffer, allocate, copy, append*, and peek* in terms of as-yet
non-existent (unsafe) primitives.
Add Buffer type and primitives to the core
Replace Fin ( n + 1 ), which doesn't reduce, with Fin ( S n )
Add C codegen implementation of buffer primitives
Remove some unnecessary copies
Missing comma
Rename functions implying Buffers have endianness

Buffers don't have endianness, though values stored in buffers do.
Endianness is redundant for Bits8
Remove redundant enName function

It's just the show instance for Endianness
Disable buffer tests on non-C backends for now
Add self to contributors