Update files to work with version 1.9.7.0

Update files to work with version 1.8.8.1

Update files to work with version 1.8.6.2

@Nupaska commented:
"""It's too slow https://goodcalculators.com/boat-prop-calculator/"""
And he was correct, so I've increased the animspeed attribute from "120" to "182.2"; this increases the visual RPM at max speed from 2400 to the requested 3644. Thanks Nupaska!

@lumen asked an important question:
"Can I add this mod to an existing campaign?"
I didn't know the answer to that, so I had to run some tests.

Version 1.0.5 only worked for new campaigns, and new ships bought in pre-existing campaigns - but for some reason the currently active ship in the campaign always failed to update correctly.

I believe I've fixed that by setting the "gameversion" attribute of the relevant <Upgrade> elements to the games current version plus one.

I'm not sure if that's how it's even meant to be used - but its worked flawlessly on my end, I even double and then triple checked just to be sure. Now its time for some of you brave mariners to put it to the test!

Shaved another 300kb(~48.780% reduction) off of the propeller textures by using png-8. The visual difference is practically undedectable. Thanks to this suggestion from @Kookoorooza, the goal of reducing the total filesize to less than 1mb has been achieved. : D

Shrunk the shuttle propeller sprite from 1024x1024 pixels to 512x512 pixels. There is no change in the visuals whatsoever, because the trimmed pixels were all transparent. The filesize is now at 1MB.

Shaved a approx 0.093MB of the mod by flattening the file structure and saving the main textures with more aggressive compression settings, bringing the total size down to 1.02MB. The visual difference is practically undedectable.

Changed description to be more concise.

Public Release