TEST DIFX using "Synthetic" data

In this directory is a script to use "generateVDIF" do create fake VDIF data
with a variety of differenr properties (real, complex, USB, LSB etc). Then the
files can be cross correlated to check DIFX is properly handling the different
setups. The "location" of the antenna is quite close together to result in a
small (but non-zero) fringe rate. This will result in a slowly varying phase.

createData.sh will generate the data. By default it will use 20min, but this
can be reduced to speed up generation time. Do not increase beyond 1200 sec.

run-all.sh will run DIFX 7 times for a bunch of different combinations and
generate an IDI-FITS file. No attempt is made to compare the correlated data.

The specfic tests are:

run-usb.sh			2 real USB real sets
run-lsb.sh			2 real, USB vs LSB
run-usb-complex.sh		Real USB vs complex single sideband (USB)
run-lsb-complex.sh		Real USB vs complex single sideband (LSB)
run-usb-dsb.sh			Real USB vs complex double sideband (USB)
run-lsb-dsb.sh			Real USB vs complex double sideband (LSB)
run-complex-complex.sh		Complex USB vs Complex USB (single sindeband)