6ba7758b30 Improve array macros (Tobin C. Harding)
Pull request description:
Currently we have two macros used when creating array wrapper types, one is in `internals` and the other in `bitcoin::internal_macros`. It is not immediately obvious what is what and why there are two.
Improve the macros by:
- Move the inherent functions to `impl_array_newtype`
- Use `*_byte_array` for the names instead of `*_bytes`
- Re-name the other macro to match what it now does
ACKs for top commit:
apoelstra:
ACK 6ba7758b30
Tree-SHA512: 36ed0fae0d28f24d29287062eb05bbc1e9e8b565f4ff41fd893503a25404ed8e185a34d75e398a8a660923ffda3b832b6157011598d5a75a5c4aafdffc74af2a