Demo updates/tweaks/improvements

I've not yet committed fully to making this into a complete game, but that hasn't stopped me from pulling up the hood and tinkering with things. The HT3DR demo has been updated with the following changes:

• The utility Tether has a new quick-tether feature. When you approach a crate, you can now hold the right mouse button instead of clicking it to invoke the tether. If you do this, two things will happen: it will enable you to un-tether by letting go of the right mouse button a moment later, and it will reduce the drag on the tank as it moves. This doesn't represent a huge change for crates, but it does help with a new stationary tether target I've been testing, which lets you quickly connect, keep most of your momentum, and release to slingshot around corners.
• Enemy pathfinding has been greatly improved. The enemies are no longer shy of going through doors, and (usually) don't bounce around like fools when they get near them.
• Power-ups are now "magnetic". There are a total of two basic power-ups in the HT3DR demo, both of which instantly max out your health. Previously, they were a little hard to pick up, but they will now automatically pick up if you get near them.
• Most objects now have a height to them. This mainly applies to the bouncing bullets shot by the "launcher" enemies, which will no longer clip through doors and should react better to windmill inhibitor blades (the big spinny things).
• Lighting is more accurate. The light source for the world is now accurate to the skybox.
• The opening cut-scene is now skippable. Pressing and holding any key on the keyboard will now let you skip most of the opening cut-scene.
• Debris spawned when enemies explode now carries some momentum with it, so if an enemy is moving around when they die, their debris will go flying off in that direction.
• Made a few graphical improvements to the Grinder boss:
  • The grinder drums now carry their momentum when they explode, so they don't clip into the boss if you blow them up as it is approaching you.
  • The grinder drums now explode if they reach a certain point of the boss corridor.
  • The grinder boss death sequence is slightly different, with explosions happening at different times and a more epic final explosion, with extra screen coloring and particles.
• Added some more video options to the config.ini file.
• Tons of various changes under the hood for shader optimization, code consolidation, etc.

Known bugs:

• The camera clips into walls sometimes and can bounce around in the wall concave corners. This is a regression that was introduced after I added some flags to the colliders to help with bullet collisions, and I'm looking into this.

If you try out the new demo, I'd love your feedback, of course. Thanks for checking it out!