* Remove wxDC and EDA_DRAW_FRAME parameters from SCH_SCREEN::SchematicCleanUp()
function call.
* Update all code that calls SCH_SCREEN::SchematicCleanUp() with wxDC and/or EDA_DRAW_FRAME
parameters.
* Fix a display refresh bug when incrementally inserting bus entries created in my last commit.
IsDanglingStateChanged() appears to be broke for bus entries.
* Remove wxDC and EDA_DRAW_PANEL as parameters from function
SCH_SCREEN::TestDanglingEnds().
* Change SCH_SCREEN::TestDanglingEnds() to return the connection change state
rather than the dangling end status which wasn't used anywhere.
* Update all calls to SCH_SCREEN::TestDanglingEnds() to remove wxDC and
EDA_DRAW_PANEL parameters and refresh connection indicators only if a
connection state change occurred.
* Add function to get a list pointers to this sheet and all of it's sub-sheets
to SCH_SHEET.
* Remove unused function SetFootprintField() from SCH_SHEET_PATH.
* Add code to SCH_SHEET object to clear annotation.
* Change SCH_COMPONENT::GetPath() to derive path from SCH_SHEET object instead
of SCH_SHEET_PATH object.
* Remove clear annotation code from SCH_SCREENS object.