Added a new key setting allowing simultaneous presses of the main shot and sub weapon keys with button 1.
X-BOX Controller: X button
Switch Pro Controller: Y button
PlayStation 4 Controller: Square button
Keyboard: / key
These are treated as simultaneous presses.
However,
for Charge Beam (5) and Gatling Gun (6), since the main weapon and sub weapon conflict,
they are not treated as simultaneous presses with this multi-key function.