Fixes #76.
Closes #17.
Closes #78.

#77
Closes #79.
Initial relations experiments.
Some test fixes.
Closes #82.
Closes #83.
Further simplified error handling. #82.
Added documentation for relations.
Merge pull request #80 from jmdobry/feature-relations

feature-relations
Closes #23. Closes #84. #77.
Merge pull request #77 from jmdobry/0.10.0

0.10.0