enh: new entities

* new entities: standard error, resMS, stat_image_properties
* couple of fixes for excursion_set_it.
* update of provn, json and ttl serializations and pdf and svg exports.
Merge
fix: add placeholder to avoid error in provToolbox
add: estimation process
fix: update excursion set file name
Add separate coordinate for center of gravity
Merge branch 'fslUpdate' of https://github.com/cmaumet/ni-dm