Introduce the new NSX data storage format v1.0 (Backward-incompatible)

• The structure of the NSX data storage format is simplified and improved.

  • A version string is added to distinguish different formats.
  • Meta and Info are merged into Metadata group. The former restriction of string metadata to 80 chars is removed.
  • The counts data are stored with the keyword Dataset to preclude possible name-clash with other group names.
  • The peak metadata use the same data structure (MetaData) as other metadata.
  • The peak metadata are stored as attributes to the PeakCollection group.
  • Group names are improved to denote their intent properly.

  Structure v1.0:
  /DataCollections
   ./<datacollection-name>
     ./Dataset
     ./Detector
     ./Sample
     ./Metadata
  ...
  
  /PeakCollections
   ./<peakcollection-name>
     ./Center
     ./Metric
     ...
     ./DatasetNames
     ./UnitCellNames
   ...
  
  /UnitCells
   ./<unitcell-name>
     ./accepted
     ./rejected      
  ...

• Removed duplicate code to export/import HDF5 files in order to avoid inconsistencies.

• Removed the legacy HDF5 reader to have a single data storage format.

• All keywords (including YAML and HDF keywords) are declared as constants in a single module (core/raw/DataKeys.h). No literal strings are allowed as keywords anymore. This avoids redundant and duplicate keywords which had caused confusion (eg., the confusion between file_name, filename, real_path and original_filename).

• Removed duplicate instances of HDF5 Blosc-Filter definition. A dedicated module, HDF5BloscFilter, is used to avoid resource leaks.

  TODO: Make HDF5 Blosc-Filter a singleton to acquire and release Blosc resources only once.

• Added dev scripts to convert datafiles to the new NSX format v1.0. HDF5 files in test folder are already converted to version 1.0.

• Corrected the initialization of some classes.

  TODO: Some classes (like DataSet) are 'half-initialized' and could accessed while still in an inconsistent state. Their finalization depends strongly on the precise order of statements (e.g., whether IDataReader::end is called yet). This produces many obnoxious crashes and should be systematically corrected.

• Improved variable or keyword names to denote the intent properly; e.g.,

  original_filename => sources
  group_name => dataset-name
  npdone => number-of-frames
  type => peak_type

• Updated HDF5 test files to NSX v1.0.