Move compression, point2oct and oct2point functions into separate files.
Add a flags field to EC_METHOD.
Add a flag EC_FLAGS_DEFAULT_OCT to use the default compession and oct functions
(all existing methods do this). This removes dependencies from EC_METHOD while
keeping original functionality.
Backport from HEAD with minor changes.
Binary compatibility is not affected as this will only be
compiled in if explicitly requested (#ifdef EC_NISTP224_64_GCC_128).
Submitted by: Emilia Kasper (Google)
key ASN1 handling through a single EVP_PKEY_ASN1_METHOD structure and move
the spaghetti algorithm specific code to a single ASN1 module for each
algorithm.