Add a layout, or layout option for PyDMFrames, that allows stacking widgets

[Ryan-McClanahan]

What's the problem this feature will solve?

Currently the only way to stack widgets on top of each other in a layout is to use a container widget without a layout inside of a layout. There are a couple of problems with this approach.

• It is not the most obvious approach, which leads to people not knowing how to do it.
• Proper minimum sizes need to be set on the container widget without a layout, or else the widget can be cut off. This can be confusing to new and experienced developers.
• The widgets inside the container widget without a layout do not scale with the rest of the page. This leads to the finished product not behaving as nicely as desired.

Describe the solution you'd like

Adding a layout option for PyDMFrames and/or a layout that allows stacking widgets in the same cell would make development faster, easier, and less confusing. Additionally, the pages developed with pydm would be a lot cleaner, as the stacked widgets would properly scale.