SST Beta 0.9 (a.k.a Smoked Sausage Tiramisu)

Another very late update, although also a pretty massive one.

I'm just gonna put in the same changelog from the in-plugin update
notes, because it's tired and I'm late. I should probably just do the
same thing from now on because it's a lot easier actually.

Here goes:

* Fixed the plugin crashing on game exit - sorry for that, everyone!

* Fixed a crash under Wine/Proton

* Fixed sst_l4d_quickreset in L4D1 No Mercy

* Added sst_inputhud to visualise inputs in-game or in demo playback

* Increased sst_mouse_factor limit from 20 to 100

* sst_l4d_testwarp now performs the take-control unsticking step by
  default

* Added sst_l4d_previewwarp to visualise warp unsticking logic

* sst_l4d_quickreset now fixes the Swamp Fever/Crash Course "god mode
  glitch"

* Added a fix for lag/stuttering in newer L4D2 versions caused by addon
  loading

* Added a fix for disabling all addons in L4D2 requiring a game restart

* Removed multiplayer chat rate limit in L4D series and Portal 2

* Made L4D1 demo playback backwards-compatible for Steam version demos
  (1022+)

* plugin_unload now displays an error when used incorrectly (without a
  number)

* Improved error messages in the event of functions failing to hook

* Rewrote and optimised a whole bunch of internal stuff

Many thanks to aciidz and bill for doing a TON of work on this,
including a ton MORE work working around stupid stuff I did when
tired/distracted/etc. This release wouldn't have nearly as much good
stuff without their help!

Thanks, and have fun! :^)