Lowers "pressed" threshold when emulating a button via controller joysticks.

[Gazzini]

Problem:
When using some external controllers (in my case, an Xbox One S controller), the cDown and cRight mappings did not work during emulation.

As it turns out, when mapping a continuous input (for instance, a joystick) to a discrete input (for instance, a button), a value of 1 is considered pressed, and any value less than 1 is considered not-pressed.

This would be fine in an ideal world, where controllers send a range of [-1, 1] for both the x and y axis. That is what the code expects, and once the joystick is extended all the way to the edge in any direction, it registers an absolute-value of 1, resulting in a press for whatever button is mapped to that direction.

Annoyingly, my controller actually sends a range of about [-.99, 1], meaning that even when I extend the joystick all the way to some edges, it's about .01 away from actually registering a click.

Solution:
Apply some rounding to any values being sent to a discrete input. This means that the press will register after a value of 0.5, which happens when the joystick is moved halfway to the edge.

Possible Future Improvements:

• 0.5 might not be the optimal threshold for registering a press. It's a bit subjective, but something closer to 0.8 might be more comfortable for some players.

• This logic might belong "lower" in the stack -- for instance, in a particular emulatorBridge.activateInput() implementation.