Elliptic curves over GF(p), new BIGNUM functions, Montgomery re-implementation.

These new files will not be included literally in OpenSSL, but I intend
to integrate most of their contents.  Most file names will change,
and when the integration is done, the superfluous files will be deleted.

Submitted by: Lenka Fibikova <fibikova@exp-math.uni-essen.de>