Auto-select UseGetWave when InitReturnsImpulse is false.

[capn-freako]

Describe the bug
Currently, the UseGetWave checkbox is left cleared, even for IBIS-AMI models with InitReturnsImpulse set to false, which is an invalid PyBERT configuration.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
UseGetWave should be forced true when the IBIS-AMI model has InitReturnsImpulse set to false.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: [e.g. Windows, Linux, or MacOS]
• Python Version [e.g. 3.7.4]
• PyBERT Version [e.g. 3.3.0]

Additional context
Add any other context about the problem here.

[capn-freako]

Fixed by f800d20.