Add switch to QGCExternalLibs.pri to check whether 32bit or 64bit version of SDL should be used on windows

Even though it hasn't been supported forever, the files where still
being compiled

No signing support yet

This way QGC can support both PX4 and APM Flight Stack messages at the
same time.

Mostly accomplished by delay loading Qml elements

- Delete all old map code

- Local 3d View
- Custom Tool Widgets
- MockUAS/MockUASManager

Adding Issue #1157 to put back

This is the Pixhawk research board, not the PX4 production board.

Our included make file doesn't build for 64-bit.
We actually need better selection on Windows and Linux platforms for building 32-bit or 64-bit versions.

This causes problems for some systems with Qt5 and Qt4 installed (like Fedora 20).

Added an exists() call beforehand.