3mf support, bug fix

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//New in 1.12 => improve auto_zoom algorithm by Michal Jirku (https://wejn.org/2020/12/cracking-the-threejs-object-fitting-nut/)
//New in 1.12 => "dispose" function
//New in 1.12 => fixed memory leak on "clean" function (thanks to Anthony https://github.com/antho1404)
//New in 1.12 => use 'fetch' instead for xhr when possible (thanks to Anthony https://github.com/antho1404)
//New in 1.12 => added get_vsb_blob (returns vsb file as binary)
//New in 1.12 => set viewstl to take all of the container (and not 5px margin)
//New in 1.12 => fixed bug in json_without_nulls function

Add files via upload

Add files via upload