New x-engine for narrowband with 4k chans.
Small fixes to narrowband 4k x-engine.

Registers had to be updated to remove xblocks debacle.
Xengine core was trying to parameterise inside a library block.
Missed the names of some registers when fixing them.
OH-mode fengine models added.
Updated delay-tracking indexing.
Merge branch 'master' of dbelab00:kat7
Merge branch 'master' of github.com:ska-sa/kat7_fpga
Wideband beamformer

16 input (8 inputs per polarisation) input frequency domain beamformer combined
with standard CASPER fx correlator.

Each correlator x-engine has a matching  b-engine taking the same data
and producing the required number of beams
(one per polarisation in this release). Each polarisation is treated
as a separate beam.

Frequency components from different antennas can be multiplied with independant
weights before summing.

Independent beam steering is not yet implemented (beam centre is the
same as the correlator output).

The data streams from the correlator and beam
formers are multiplexed through a 10Gbe output interface and are all
packaged in the SPEAD format.

bf_functions.py in the CORR python package contains related software control.
All functionality has been sanity checked with detailed data analysis to follow.

An 8 input (4 inputs per polarisation) version is included and allows sharing of correlator
hardware resources during testing and development.
Merge branch 'master' of github.com:ska-sa/kat7_fpga