Saving mask results in FITSIO error

[MatthewWhiting]

I am sometimes seeing an error when saving the mask:

WARNING <saveMask> : Error writing mask array!:

FITSIO status = 412: datatype conversion overflow
Numerical overflow during type conversion while writing FITS data.

It seems to only happen when flagMaskWithObjectNum is set true.

[MatthewWhiting]

Have changed the format of the mask FITS file, so that we save it as integers rather than shorts. This was done in [1100].

In that same commit I improved the function calls to write the other FITS file arrays, making them consistent (using fits_write_imgnull_flt and so on, with the type explicitly given in the function name).

It may be worth thinking about doing a similar refactoring to the reading of FITS files (reading recon/smoothed arrays), but this may be a bit more complicated...

[MatthewWhiting]

Actually, keeping the code as is for now (1.2.2). Will make a new ticket for 2.0 to refactor this code - can evaluate later.