ecdsa: do not abort on compressed pubkeys
implement ecdsa key support
rename keytype to keyformat and introduce enum

Since the RFC also names it key format.
net::ssh: update stdlib changes
remove unused dependency
harden against "compromise via lattices"
make write functions return number of bytes written
update to latest stdlib changes
fixes to work with latest hare updates
memio changes i've missed
update to os::signal changes
update to memio
fix uninitialized values

This is a dirty fix to make it compile until a better solution/pattern
is found.
rsa: fix clearing privkey params on decode
export ssh::format::newkey
format::ssh: close base64 encoder at right moment

otherwise the padding will be written after the comment.
format::ssh: add rsa key support
Updates per crypto::aes changes
format::ssh: factor out newkey, free keys on err