How to install

(written on tiger)
Fix g++ warnings
os/x isn't case sensitive.  The file is "wcs.i"
We need to link the fftw_float libraries.

N.b. should add a feature to sconsUtils to suppress the resulting warning:
  Could not find EUPS product dir for 'fftw_float'; using /home/astro/hsc/products/Linux64/fftw/3.3.2
Oops.  The returned std::vector<> goes out of scope, leaving a dangling refernce
Set the gain from the Detector, if it's set
FWHM is a double, not an int
We test for the value of psfCellSet, not its existance.
When the stamp fell partially off the chip, indexes such as -1 were interpreted
relative to the right/top of the image, resulting in memory corruption

Also added a check to protect against this corruption.
Enforce normalisation to unity
Get the XY0 value right to put the peak in the requested pixel
Reset prefs for every field
Fix centering of the PSF and Kernel images
Added tests for PsfexPsf
Handle bad mask bits in psf candidates

N.b. We now use the psfCandidate image, which has INTRP set to label
contamination from neighbours
Fixed unnecessary transposing, as shown by tests/testPsfexPsf.py
Return to quadratic interpolation
Generate docs
Updated after building on a unix box (tiger)