Refactor subsystems into cores, auto constraints

Refactor the pre-FFT logic into the 'adc_preproc' core. Adding
noise switching, adc level detection.

Move FFT auto-correlation power block into 'auto_core' also
adding noise demodulation capability (though currently with
no compensation on the noise switch timing for the latency
incurred by the data through the FFT). This block (unlike the
old code) does all frequency channels, and has programmable
accumulation length.

Swap constraints to use those auto-generated by python scripts,
and change leftover constraints so that the modelname is
wildcarded (so the ucf doesn't need customising on every
model name change)

Compiles at 2.5GHz adc clock, and with auto constaints seems
relatively tolerant to code changes
Added latest boffile

ami_fx_sbl_nofs/bit_files/ami_fx_sbl_nofs_2014_Sep_30_1526.bof
compiled @ 2.5GHz adc clock