This patch adds bindings to the PK part of the Olm library contained in
the pk.h header file.

Encryption, decryption as well as pickling/unpickling of the decryption
object is supported.

Signed-off-by: Damir Jelić <poljar@termina.org.uk>

Typing is part of standard library from python 3.5 and from python 3.7
onwards trying to install it results in an error.

This patch disables typing installation on python versions that are
newer than 3.5.

Signed-off-by: Damir Jelić <poljar@termina.org.uk>

Add signing class to the pk module

because emscripted has dropped support for the old flag and us
setting it is now breaking the build.

This is a workaround for a bug where signature verification would
overwrite the variable holding the signature.

This only happens on python2.

Signed-off-by: Damir Jelić <poljar@termina.org.uk>

OLMKit: Expose PK private key length

CMake support

OLMKit: Add objc wrappers for pk encryption/decryption

zero buffers in the JavaScript bindings

Poljar's improved python bindings