Adds separate bindings for each of the pad types (DualShock2,
Guitar,Pop'n Music). This allows the user to change the button
configuration to better suit the Guitar and Pop'n Music pads without
messing up the bindings already setup for the DS2.
Close#1576.
Windows Vista onwards provides application specific volume controls, and
the local volume feature only interferes with it. Any volume adjusting
stuff probably belongs in SPU2-X.
Closes#629