Demo Update - Walljumping, sliding, tutorial, firing range, and more. — Dragonfly Steam update #1408724

Worked on the demo some more, apologies for the long delay.Additions include:-Tutorial mission-Walljumping for a speed boost-Sliding to preserve momentum-Tweaked enemy AI, they should be more aggressive now-Reimplemented remote demolition charges in place of the frag grenades-Adjusted weapon balance-Adjusted map flow and geometry- there's an alternate path in the first mission from the bottom area now-Leaning is more useful now-Firing range added after completing the demo-UI tweaks-Added options to invert mouse aim on individual axis-Accessibility options to add a reference crosshair in the center of the screen and adjust screenshake-You can use the mouse wheel to scroll through weapons now-Adjusted heartbeat sensor mechanics, now only visible in reflex mode, where they're always visible.-Tweaked particle effectsAnd some other minor fixes. Thanks for taking the time to play my game!