feat(optimizePathOrder): new plugin

[KTibow]

Paths can often be optimized by changing their direction.
Base path: M16 14v-2H8v2Z (14b)
Optimized by changing the start: M8 14h8v-2H8Z (13b)
Optimized by reversing direction and changing the start: M8 12h8v2H8z (12b)
This plugin automatically does that!

Flow of the plugin:

• For each path, break it down into "parts". Each part is a continuous set of instructions. Parts are "valid" if they contain only instructions that we can move around and reverse properly.
• Send it off to be optimized
  • Remove the args, we'll recalculate them with coords. Any args that have special meaning go into a special property.
  • Disable changing the start if it has a non-round stroke, or if the part isn't closed.
  • Disable changing the direction if the fill rule is nonzero and there's more than one part in the path.
• Try with reversing (if available) and without reversing
  • Input: reverse the base and coords, and reverse the order if we're reversing this time
  • Output (mutable): an actual set of path commands.
  • Iterate through the possible orders
    • We essentially want to move the first command to the end
    • Remove the first command
    • Adjust the move command to move to the new first command's base, so that it isn't broken
    • Remove the previous last command and re-add it, except this time it can't be z
    • Add the new last command
    • Estimate the length of this new output. If it's better than anything so far, use it.
• Reconstruct the path from parts
  • If the optimization gets something better than the original, use that
  • If it doesn't or the part was "invalid", use the original

Closes #1847
Closes #78 (damn thats old)

This is an optional plugin. Recent changes have made it fast enough to run on very large files in 100ms though.

Results

Name	Standard	Multipass
Arch Linux logo	-95b	-102b
Blobs	-116b	-117b
Isometric Madness	-1637b	-2563b
tldr-pages banner	0b	0b
Wikipedia logo	-481b	-502b

* Those results are outdated, after merging the latest changes I think something elsewhere changed making it less efficient

[KTibow]

If I don't do this, whenever I set an exact value for an argument it leaks out, despite my plugin having a default set. (js2path stores the value exactly, and if it gets called later with a different precision it overrides.)

[anthonyryan1]

I just thought I'd chime in. This is the first plugin thing I've seen in years that could improve the compression of a few of my hand-optimized ultra small files.

I had previously thought there was little more optimization potential in them.

Great idea