App switching support

[abraha2d]

Note: Also contains a fixed version of #157. Should probably reach a resolution on that before this one.

This pull request allows for one to switch multiple applications in one go by setting Alt+Tab OnInterval in one direction, and Alt+Shift+Tab OnInterval in the other direction.
Fixes #35. It also addresses some related issues that I encountered (fixes #118 and fixes #128).

These changes will break any use case that requires being able to do gestures on multiple axes during one gesture button press. I can't think of any use cases that need that functionality, though.

Changes:

• GestureAction: Restrict movements to a single axis after threshold is reached (issue Few pixels doesn't prevent OnRelease from triggering #35, useful for preventing unintended gesture activations)
• GestureAction: Don't wait till origin before switching directions (issue Gesture reaction time #128, useful when both directions affect the same state like changing volume or switching workspaces)
• IntervalGesture: Fire action as soon as threshold is reached, instead of waiting for another interval (issue Gesture reaction time #128)
• Added halfRelease method from IntervalGesture to Action to KeypressAction (issue Allow define prefix keys in gesture actions #118, useful when the OnInterval actions for an axis require holding a key down, like Alt+Tab and Alt+Shift+Tab)

Sample config for application switching:

devices: (
{
    name: "M720 Triathlon Multi-Device Mouse";
    buttons: (
        {
            cid: 0xd0;
            action = {
                type: "Gestures";
                gestures: (
                    {
                        direction: "Left";
                        mode: "OnInterval";
                        interval: 150;
                        action = {
                            type: "Keypress";
                            keys: ["KEY_LEFTALT", "KEY_LEFTSHIFT", "KEY_TAB"];
                        };
                    },
                    {
                        direction: "Right";
                        mode: "OnInterval";
                        interval: 150;
                        action = {
                            type: "Keypress";
                            keys: ["KEY_LEFTALT", "KEY_TAB"];
                        };
                    }
                );
            };
        }
    );
}
);

[bdavj]

Running @abraha2d 's branch to try and sort smooth volume operations on thumb button. Can confirm fixes for #128 greatly improve usability for volume operations.

[T99Rots]

Just locally rebased this branch in to master and can confirm everything still works perfectly and it still fixes multiple issues, would definitely like to see this branch merged @PixlOne