Hepdata-converter

- FIX Fixes issue with ROOT conversion and null values
- ADD Allows phrases to be given by phrase attributes tag

FIX: Fixes problems caused when writing over an already existing file.

Signed-off-by: Eamonn Maguire eamonnmaggmail.com
Co-authored-with: Graeme Watt graeme.wattdurham.ac.uk

- Faster dumping of records to YAML using CDumper.

Signed-off-by: Eamonn Maguire eamonnmaggmail.com

Allows for use of the CLoader from libyaml if present.

Slimming down of dependencies made with removal of numpy and rootpy.

yoda writer: remove space in table name written as Title
- avoids bug in YODA 1.6.0 (to be fixed in next release).

Signed-off-by: Graeme Watt graeme.wattdurham.ac.uk