In pitch fly mode, you fly to the exact direction you are pointing at, using the forward key. Other move directions are also pitched accordingly.
It allows smoother and more complex movements.
Can be enabled/disabled by L key by default (set keymap_pitchfly in minetest.conf)
* Make InputHandler own the key cache
* Add a helper function InputHandler::cancelPressed to avoid multiple similar calls in game.cpp
* Move RandomInputHandler::step definition into cpp file
* Various code style fixes
* Use range based for loops
* Use empty instead of empty objects
* Use C++11 default keyword for trivial constructors and destructors
* Drop some useless casts
* Use emplace_back instead of push_back to improve performance of some vectors push
* Move KeyList & InputHandler from game.h to client/inputhandler.h
We have a header for inputs, move inputhandler class & related keylist object to it
Also introduce a cpp file for MyEventReceiver::OnEvent function in inputhandler.h because a so huge function doesn't needs to be inlined
* Pass clang-format on inputhandler.{cpp,h} (compatible)
