Molecule aware array parameter is not initialized

[sverhoeven]

After #62 the form is invalid for flexref using expert catalog.

To replicate

1. Choose haddock3expert catalog
2. Load the docking-protein-ligand example (button on bottom left of page)
3. In the middle workflow column select the flexref node
4. In the form press the submit button
5. At top of form you get list of errors, which is unexpected

Workaround

1. Expand Flexibility sub form
2. For seg parameter for both molecules add a row and remove it again
3. For fle parameter for both molecules add a row and remove it again
4. In the form press the submit button
5. Form is valid

[sverhoeven]

Resolved in #62