Joystick tweaks.

Ensure that the joystick can always reach -1.0, 0.0 and 1.0 positions
even when noise filtering is applied.  (Bug: 3514510)

Add support for a few more standard axes.

Add additional mapping modes for axes.
Some axes are inverted from standard interpretation
or are actually intended to be split into two distict axes
such as left/right trigger controls or accelerator/brake.

Add key layout file for a G25 racing wheel and XBox 360 controller
to tweak behavior.  They work fine without them but the axis mappings
are not ideal.

Change-Id: Id4c86a0a272331c680039a9bde6815bb7eba44ab
diff --git a/data/keyboards/Generic.kl b/data/keyboards/Generic.kl
index 33947e7..68a158e 100644
--- a/data/keyboards/Generic.kl
+++ b/data/keyboards/Generic.kl
@@ -426,6 +426,10 @@
 axis 0x03 RX
 axis 0x04 RY
 axis 0x05 RZ
+axis 0x06 THROTTLE
+axis 0x07 RUDDER
+axis 0x08 WHEEL
+axis 0x09 GAS
+axis 0x0a BRAKE
 axis 0x10 HAT_X
 axis 0x11 HAT_Y
- 
\ No newline at end of file