[DO NOT MERGE YET] Add More Pixel Art Upscaling Algorithms (#1152)

[DO NOT MERGE YET] Add More Pixel Art Upscaling Algorithms (#1152)

* Start extending magnify function

* Fix pixel alignment

* Reimplement scale2x in a new function

* Create IntensitiesEqual function

* Implement eagle algorithm

* Retrieve magnification alg from -define

* Make use of -define with -magnify

* Make use of magnification variable

* alg -> method

* Implement scale3x

* Implement eagle3x

* Compare pixels by channels

* Implement eagle3xb

* Implement EPX

* Start implementing hq2x

* Fix hq2x

* Fix formatting

* Add const qualifiers

* epx -> epbx

* Implement XBR

* Fix XBR

* Implement fish

* Fix indexed color bug

* Refactor