Bump version to 0.2.7
Support histogram BRAMs in adc16_test model
Make adc16_init print user register settings

When using the -r option with adc16_init, it will now display the
registers and values that the user requested to be set.
Change ADC16Test::DEFAULT_BOF to adc16_test_rev2x8

Now defaulting to adc16_test_rev2x8 since it will be rare to find a
ROACH2 rev1 (all destined for SMA) with an ADC16 card.
Make ADC16Test::Histo#histo return NAarray::FLOAT

In order to treat the 32 bit histogram values as unsigned, it is
necessary to use NArray::FLOAT since the NArray::INT is signed and
therefore limited to a max value of 2**31-1.  Futhermore, adding 8 such
values together in NArray::INT could overflow.  Using NArray::FLOAT
avoids these issues since it can represent integers exactly from -2**53
to +2**53 using 64 bit double precision.
Add histogram support to adc16_plot_chans.rb

Plots historgram values from snapshot buffers.  Lengths 1 to 1024 work
with any ADC16 design (using built-in snapshot buffers).  Lengths 1025
to 65536 work with the adc16_test design (or compatible design).

This does NOT use the histogram gateware of the adc16_test design.
Improve Adc16Test::Histo class

It now extends KATCP::Bram allowing it to be read directly like a Bram.

It now properly unwraps negative values.
Fix error checking in ADC16.chip_chan
Include stats by default in adc16_plot_chans.rb

The stats used to be off by default, but now they are on by default.
Zero-out DC channel on frequency plots

The DC channel tends to dominate the other channels and is not so useful
to see, so we zero it out before plotting (but still include it in
stats).
Change histogram overlay color to dark gray

This prevents the overlay from visually dominating the plot.
Remove commented-out code
Make adc16.rb require 'adc16/version'

This makes version info available in ADC16::VERSION.
Bump version to 0.2.8
Bump version to 0.2.9