Ground-Plugins-Created gcscontrolplugin

Provides a GCSReceiver API
ground-plugins-gcscontrol renamed to gcscontrolwidget
Ground-plugins-gcscontrol- made gcscontrolwidget use the gcscontrolplugin API
ground-plugins-gcscontrolwidget-renamed gcscontrolplugin to gcscontrolwidgetplugin
ground-plugins-gcscontrol add timer to periodically send gcsreceiver

This is needed in order to not trigger failsafe.
ground-gcs-plugins-gcscontrolwidget fixes compile issue with USE_SDL=TRUE
ground-plugins-gcscontrolwidget added gcscontrolplugin as dependency
ground-plugins-gcscontrol completed file header information
ground-plugins-gcscontrolwidget removed unused function
GCS Controller: 1) Fixed debug build issue. This was due to an improper
pluginspec file.
2) Removed object from plugin manager when plugin destroyed.
Merge pull request #990 from TauLabs/gcs_refactor_fixed

GCS Receiver API and GCS Control refactoring