Blender Git Loki

BGE patch: Add level option on sensor and fix sensor reset.

Level option is now available on all sensors but is only implemented on
mouse and keyboard sensors. The purpose of that option is to make
the sensor react on level rather than edge by default. It's only
applicable to state engine system when there is a state transition:
the sensor will generate a pulse if the condition is met from the
start of the state. Normally, the keyboard sensor generate a pulse
only when the key is pressed and not when the key is already pressed.
This patch allows to select this behavior.
The second part of the patch corrects the reset method for sensors
with inverted output.