work in progress about issue #110
basic test on time
saving detector description in Nexus files
issue #110
saving detector description in Nexus files ... 
writing looks OK
issue #110
work on detector read-back
Issue #110
work on HDF5 saving of detectors
Merge branch 'master' into issue_110
lot of work done: all detector can now be serialized to/from disk.
ImXpad flat detector which is made of non-connected modules
all detectors now look OK.