This checks that the protobuf is the right form, also handles uncompressed
keys (though you shouldn't be using those any more, should you?)
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
DER encoding introduces problems for non-canonical encodings; we should
do that only at the lightning<->bitcoin interface.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
