🔥 Performance improvements

[argyleink]

over time the selection and gui creation mechanisms's responsibilities were spread out. they've been unified where appropriate, resulting in multi-select, search queries, or anything that creates alot of gui, being 50% or 100% faster. Extreme cases are 80 nodes drawing their gui at 30ms or so, vs 80 nodes at 100ms

try it: https://visbug-perf.glitch.me

changes:

• bulk and async getBoundingClientRect
• single document.body incision for appending visbug gui

fixes #112 fixes #225 fixes #160

before

after