This closes #1169, initialize add form controls supported

- Breaking changes:
* Change
    `func (f *File) AddShape(sheet, cell string, opts *Shape) error`
    to
    `func (f *File) AddShape(sheet string, opts *Shape) error`
* Rename the `Runs` field to `Paragraph` in the exported `Comment` data type
- Add new exported function `AddFormControl` support to add button and radio form controls
- Add check for shape type for the `AddShape` function, an error will be returned if no shape type is specified
- Updated functions documentation and the unit tests