64f7d2549e Fix wrong newtype APIs (Martin Habovstiak)
Pull request description:
This fixes several API bugs:
* Use `TryFrom` instead of `From` for fallible conversions
* Move byte conversion methods from `impl_array_newtype` to `impl_bytes_newtype`
* Add missing trait impls like `AsRef`, `Borrow`, their mutable versions and infallible conversions from arrays
Closes#1336
Notably this change is much less bad than even I expected and some places actually get cleaner than before.
ACKs for top commit:
tcharding:
ACK 64f7d2549e
sanket1729:
code review ACK 64f7d2549e
apoelstra:
ACK 64f7d2549e
Tree-SHA512: 0c5ab19aa1a01ccf34ad1c2f3f66bd003a3142a840cb7cf57e1449e721f6eed1523555c62f0e3391012708767ff86315ff7edce9afd85017a67c61cfe57dddbc