Fixed truncated CPRadio / CPRadioGroup. #2182

Here is a PR that will solve our truncated CPRadio button [https://github.com/cappuccino/cappuccino/issues/2182]. It was due to a specific behaviour of CPRadioGroup.
You can check my commit messages for more details :-)

Also, I updated 2 tests that now enable to show CPRadio and CPRadioGroup behaviour:
* `Nib2CibAlignment`
* `CPControlSize`