Merge pull request #38 from jfbloom22/master

fix: should parent and control prams on FieldConfig be optional

Author: bietkul

index.d.ts

@@ -327,8 +327,8 @@ export interface GroupProps {
 }
 export interface FieldConfig extends GroupProps {
  controls: { [key: string]: any } | Array<any>
- control: FormArray | FormGroup
- parent: FormArray | FormGroup
+ control?: FormArray | FormGroup
+ parent?: FormArray | FormGroup
  options?: AbstractControlOptions
  strict?: boolean
  meta?: { [key: string]: any }