Removed commented v4 ArduPilot Quad fw links

To address issue https://github.com/mavlink/qgroundcontrol/issues/2735

Was failing on slower ArduPilot boots. Also could fail on PX4 boots
which required px4io flash on boot.

This was causing problems with auto-connect after a flash

- Fix: Version error message not being displayed
- Correct handling of APM and PX4 files with respect to home position
in first slot
- Emit newItemsFromVehicle signal so editor can fit map viewport on
load from vehicle

This provides a better workflow for firmware upgrade

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

- Also fix vehicle selector dropdown in toolbar

I know that some people belive that goto's are devil's work
but sometimes (like chaining if/elses for failures) it can
actually simplify the code for a better readability and
improved speed.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Strings can be expensive to create, all the issues with allocation,
copy of the char members, conversion to UTF-16. QStringLiteral creates
one in compile time.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

virtual marks a method for inclusion on a v-table, but we don't want
the methods of classes that won't be inheritable to have a v-table,
we want, however, to issue a warning if somebody try to inherit
that specific class and reimplement those methods.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>