psFitsImage.c / convertImageWrite not quite working

[eugene]

I disabled the quantization of the floating point images in convertImageWrite. There are some problems with it:

1) the conversion sets the bzero / bscale values, but the following code in psFitsInsertImage raises an assert on the values of bzero / bscale if they are not 0.0, 1.0. something is inconsistent here.

2) the operation needs to be optional. not all integer truncations can be treated equally. the most obvious example is in using ppImage to perform an operation on a mask image. It is necessary to tell ppImage to write out the resulting value with the mask fits type, setting bitpix to 8. However, the mask values are not a smooth data field, and must be maintained.

I have put # if(0) around the relevant code, but some work in the calling APIs is needed.