Reset the group field values each group
Use getters/setters
Unset field values prior to setting values
No need to set empty values as this is done
Simplify group get values logic
Tidy up code
Merge pull request #244 from humanmade/fix-grouped-checkboxes

Repeatable group with more than 1 checkbox renders/saves incorrect values
Merge branch 'master' into better-args-parsing

Conflicts:
	classes.fields.php