Portal: Cooperative mod

As stated in the summary, this update will probably be the last major update. The servers will also be up again.

Here's what changed:

• Added New Maps! What used to be p2coop_0 is now p2coop_3. These new maps serve as introduction levels for the mod.
• Fixed Mel using the wrong expressions after the last map transitions to the first map.
• Fixed a commentary node in p2coop_7 (now p2coop_10) having a bad speaker name.
• Fixed portal ghosts (an object's portal clone) not glowing.
• Fixed players appearing to "clip" with the portal plane.
• Fixed energy balls sometimes crashing when a player is hit.
• Updated how the game finds the colors to use for players, this will fix things like dead players using the wrong color in the hud.
• Updated the beam textures for the portalgun stream particle. This may fix missing textures for those that didn't have Half-Life 2: Episode Two or Source SDK Base 2013 Singleplayer installed.
• Added a test chamber sign for the "dummy chamber" in p2coop_6 (now p2coop_9).
• Added "use tolerance".
• Added a feature where holding a key (shift by default) will cause othe players to glow, this is a substitute for Portal 2 Coop's remote view.
• The long fall landing sound is no longer client sided.
• Removed loose chapter icon files.
• Decreased the volume for the fizzler sounds.
• The playermodels will now have their skin changed depending on what portal color set they have.
• Removed Developer Commentary (may be added back in the future).

Updates to the portals:

• Improved how portal stealing works, you no longer have to look directly at a portal to steal it, as long as the portal is in the way, it will be stolen (for the most part).
• Added portal steal particles.
• Overhauled the angle fix when walking through portals.
• Walking through portals is now less buggy, but right now, they still have a little lag.
• View model sway now looks better when interacting with portals.
• Updated portal rendering - Portal Coop used to have a different way to render for colored portals, but in this update, we've reverted back to Portal 1's rendering technique now with colored portals support.

Map Changes:

• Improved every level in some way or another to make them more fun for first time play.

SDK Changes:

• Added OnMaxPlayersTouching output for trigger_multiple
• Added OnFizzled and OnStolen outputs for prop_portal
• Added new keyvalues for all weapons
• Added new keyvalues for the portalgun
• New entity: info_player_portalcoop, can be used to set portalgun options for player spawns