Support Love 11

[Mystro256]

Just keeping this awesome game alive by updating it to love 11.

Quick summary:

• Color rgba values are now floats between 0-1, instead of integers between 0-255, so I wrote a wrapper for love.graphics.setColor for compatibility, and an adjustment for the two uses of getPixel
• love.filesystem.exists is deprecated, so I wrote a compatibility wrapper for it's replacement
• love.audio.newSource no longer assumes type, so I added stream for music, static for sfx. I think this is compatible with older versions but I didn't test with older than love 0.10.

Thanks!

[Stabyourself]

Hey, thanks for the PR

I don't think supporting more than 1 versions of löve is necessary. Of course supporting 11.1 over 0.10.2 would be preferable though.
I know I already accepted the PR that added 0.10+ support on top of 0.9 support, but I've changed my mind about this since then.

To that end, I don't think wrappers that convert 0-255 to 0-1 are a good idea. To properly support 11.1, the code should just use the 0-1 colors everywhere. Same goes for lf.exists (use lf.getInfo)

Thanks again for the PR though, if you're not up to changing it for "pure" 11.1 support, I'll take that up myself once löve.js is working well enough.

[Mystro256]

Sound good, I made another commit, but it still wraps the color code. I'll look into it later if I have time.

[CoolCat467]

Time waits for no one. I am curious of the status of this project; It is a good game.