Merge pull request #20 from agbeltran/dev

Catalog file - committed only once
Merge pull request #21 from agbeltran/dev

Changed non-simple property 'has part' to 'is about' when used in a card...
modification to textual definition based on Thomas Nichols feedback, closes#18
modification to textual definition based on Thomas Nichols feedback, closes #18
Changed restrictions to 'correlation coefficient'
Merge branch 'dev' of https://github.com/ISA-tools/stato into dev