Finish optics specs table.
Let floats float.
Finish ZEMAX parm table.
Text about optical design. Optical schematic.
Spelling
Update for zemax parms at 17 m.

The distance scale discrepancy is not as severe as I had thought,
because focusing at 17 m *should* increase the scale. Doesn't account
for the entire difference, but still helps.
Start working on feedhorns again.
Add marginal rays, f-number to zemax parms table.
Nice plot of feedhorn efficiency.
Ignore tmp file for contour plots