[IO] FIO files: handle missing data

[tifuchs]

Hi silx team,

I have encountered FIO files with entries like

  -89.99999279994226 -89.74998879491014                1                  <no-data>      <no-data>   
  -89.74998879491014 -89.4999937899502                 2                   1                    120.9696655273438
  -89.4999937899502   -89.24998978491807               3                   1                    120.9657211303711 

which cannot be read in the current implementation of fioh5.py.

Suggested fix

Use numpy.genfromtxt instead of numpy.loadtxt in fioh5.py,

silx/src/silx/io/fioh5.py

Line 260 in 415b020

self.data = numpy.loadtxt(

which more gracefully handles missing data and automatically fills missing data with numpy.nan.

I am working on the implementation of the fix and will create a PR once the code is ready. (if this is ok for you)