In-Place Refactoring

[danielmohansahu]

The initial draft of this project is complete, but it's left with a swath of technical debt. A cleanup refactoring is in order, including (but not limited to) the following:

• Panels can be broadly grouped into non-select-able (e.g. for displaying non-select-able information, whether static or dynamic), select-able (e.g. for displaying, y'know, select-able information that we can also filter), and mixed (a hybrid). Make base classes for each of these that implement a significantly pared down API for PanelBase and then just design a construct (or similiarly named) method that does the actual writing.
• To support future improvements the core ros interface should be available to individual panels as a const std::shared_ptr instead of the ComputationalGraph product.