spherical mapping texture to skybox

[i-make-robots]

Is your feature request related to a problem? Please describe. boring backgrounds.

Describe the solution you'd like skybox 1: load 6 separate textures (exists) skybox 2: load from one large texture that has a spherical projection. convert back to 6 planes and display accordingly. survive reloads.

Describe alternatives you've considered

Additional context example textures: https://stock.adobe.com/ca/search?gclid=Cj0KCQjwj5mpBhDJARIsAOVjBdrBGxXgT2C6DHPmAYMpsvnAG7Q3n7R0pINGBdT_bmhmiEzeACgvoAoaAjIXEALw_wcB&k=skybox&ef_id=Cj0KCQjwj5mpBhDJARIsAOVjBdrBGxXgT2C6DHPmAYMpsvnAG7Q3n7R0pINGBdT_bmhmiEzeACgvoAoaAjIXEALw_wcB:G:s&s_kwcid=AL!3085!3!514860269895!!!g!!!11559576852!111491065134&as_channel=sem&as_campclass=nonbrand&as_campaign=CA|CPRO|Stock|PURCH|DSA_Website_pages|GG||&as_source=google&mv=search&mv2=paidsearch&as_camptype=acquisition&sdid=41Y39Y9C&as_audience=core

[i-make-robots]

Looks like a spherical texture map can be applied to a sphere. once the sphere radius is set to -1, the rest just works.

[i-make-robots]

Maybe if JavaHDR gets added to Maven we can read HDR files directly and use them as spherical maps.

[i-make-robots]

finished in #173