Fix WebGL clear to make background transparent instead of black
Fix WebGL clear to make background transparent instead of black

This commit is an attempt to learn contributing to github projects while following a tutorial by The Coding Train.
This commit fixes a bug found in the WebGL renderer where pixels would turn black instead of transparent on `clear()`

limzykenneth/p5.js,mlarghydracept/p5.js,nucliweb/p5.js,bomoko/p5.js,limzykenneth/p5.js,dhowe/p5.js,kennethdmiller3/p5.js,processing/p5.js,joecridge/p5.js,kennethdmiller3/p5.js,processing/p5.js,nucliweb/p5.js,dhowe/p5.js,bomoko/p5.js,joecridge/p5.js,mlarghydracept/p5.js