iterator: do not drop an error in resolver 

fix version for 0.7.4 release 

graphql: update dependency and test filter with multiple values 

bump version to 0.7.3 

schema: allow to customize behavior; resolves cayleygraph#694 

update dependencies 

add v0.6.1 migration guide; mention dataset conversion in import docs 

Tag v0.6.1 for release 

Tagging release v0.6.0 

Merge pull request cayleygraph#386 from barakmich/optional_path Add SaveOptional() to save predicates if they exist, and add the