Fix Enter key behavior in Autocomplete list

[psrok1]

Your checklist for this pull request

• I've read the contributing guideline.
• I've tested my changes by building and running the project, and testing changed functionality (if applicable)
• I've added automated tests for my change (if applicable, optional)
• I've updated documentation to reflect my change (if applicable)

What is the current behaviour?

Dropdown menu buttons have not correct type. Default button type is submit, so they take over Enter key handling after dropdown appear.

What is the new behaviour?

Added type="button" to dropdown menu buttons, so input is correctly submitted.

Closing issues

closes #401

[KWMORALE]

Now works fine