Ecies options - allow EC point compression for ECIES scheme

This change allows clients to specify EC Point Compression for the output of the ECIES encryption routine.  This reduces output by 32 bytes (for EC key size 256).  Clients specify point compression by using a newly added constructor for org.spongycastle.jce.spec.IESParameterSpec in which the last argument is a boolean flag 'usePointCompression'.

The default remains (as before) no point compression.
This change does not introduce any API incompatibilities or changes.
Point Compression works equally with streaming (xor) mode or conventional block cipher.