Added permanent debris filter to antenna target display.

Partially addresses RemoteTechnologiesGroup/RemoteTech#37.
Added ability to select target list filter using map view controls.
Added code to auto-refresh vessel list without breaking other window functions.

Includes partial refactoring and documentation of AngennaFragment class (note: diff looks more garbled than it is; the main change was splitting `Refresh()` into two functions, `Refresh()` and `RefreshPlanets()`.).

Resolves RemoteTechnologiesGroup/RemoteTech#37.
Removed redundant code I'd added.
Merge branch 'develop' of https://github.com/RemoteTechnologiesGroup/RemoteTech into hide-debris
Added @Peppie23's patch for FocusFragment.

Also changed var declarations to explicit types for improved code readability.
Merge pull request #175 from Starstrider42/hide-debris

Use map view filters to hide unwanted vessels in target list