CSSTUDIO-2648 "Add Layout" toolbar button and new "Add Layout" icon

[abrahamwolk]

This pull request:

1. Adds a new toolbar button "Add Layout":

2. Adds a new icon for adding layouts. The new icon is used both for the new toolbar button as well as for the sub-menu "Window" -> "Add Layout" in the menu bar.

The new toolbar button is disabled by default and must be added explicitly by setting org.phoebus.ui/toolbar_entries=Add Layouts.

[georgweiss]

Variable names like add_layout do no conform to Java naming convention.

Why is the button in the toolbar is a dropdown?

[abrahamwolk]

Variable names like add_layout do no conform to Java naming convention.

It conforms to the naming of the other instances of MenuButton in the class. I think it would be less readable to use camel case when the other instances of MenuButton don't use it.

Why is the button in the toolbar is a dropdown?

It's a dropdown that lets you choose the layout to be added. This is analogous to the already existing "Load Layouts" dropdown.

[georgweiss]

It conforms to the naming of the other instances of MenuButton in the class. I think it would be less readable to use camel case when the other instances of MenuButton don't use it.

I beg to disagree.

It's a dropdown that lets you choose the layout to be added. This is analogous to the already existing "Load Layouts" dropdown.

OK, I see. I thought this was about creating a new layout...