allow writing planning elements' status_id
remove obsolete planning_element_status_id
added regression test for bug #3229, i.e. for setting a planning element's status
added changelog entry
Merge pull request #738 from opf/fix/api_cannot_set_planning_element_status_3229
Creates missing work package custom values
Adds changelog entry
Merge pull request #743 from opf/migration/create_missing_work_package_custom_field_values

[Migration] Create missing work package custom field values
Fixed a bug with non-functional validation for work package parents
Merge pull request #750 from opf/fix/work_package_parent_validation

Fixed a bug with non-functional validation for work package parents
Fixed missing parent_id error
Merge branch 'dev' into feature/issue_autocomplete

Conflicts:
	doc/CHANGELOG.md