initial beam former functions

Not tested on hardware. Supports basic creation of a beamformer from
correlator, initialisation, SPEAD transmission, data transmission,
calibration coefficients.

TODO: run-time configurable bandwidth
Beamformer constants added

Correlator stuff kept as is. New beamformer section added with
beamformer related settings
Beamformer additions

Long description modified to add beamformer. Version bumped but
may need bumping again.
bf_functions added to sources
Initial and basic beamformer versions added
Initial and basic beamformer options
beng_en bit added to ctrl register bitfield

Enables 10Ge output for beamformer
Resolved conflicts while merging

src/__init__.py - added bf_functions.py and threaded
setup.py - bumped version up one as few beamformer additions
    (should not affect interface though)

Merge branch 'master' of github.com:ska-sa/corr

Conflicts:
	setup.py
	src/__init__.py