Add user folders

[josephgeis]

It would be nice if we could sort our programs into folders.

[LAX18]

It would be...

[josheewa]

Not happening.

[adriweb]

User folders have previously (calcs older than the CEs) been done using a byte in the var format that was unused. TI now uses it on the CE, thus making it impossible (that way).
I'll close that but in case @mateoconlechuga ever wants to do it in a different way, he'll probably reply and refer to it in a commit :P

[LAX18]

I figured as much... I hope to add something similar on my shell but we will see how that goes.

[josheewa]

I've asked Mateo already a long time ago, and he said he'll never add them.