Load sets of files semantically

[pforhan]

Requirements:

• load a directory w/optional file filter
• stretch: load a dir tree

example:
2dgameart bundle is typically: character/filetype/size/frameset/files_001.png
so Hedgehog/PNG Sequences/Hurt/Hurt_00*.png would hopefully translate to frames named Hedgehog-hurt-001 or something.

simplest impl would be to have a load(prefix, list) so maybe a file gatherer/visitor would be a different thing

... that said may need an abstraction layer since the files could be streaming out of an archive.

[pforhan]

fun fact, kotlin has a nice visitor for files in its file.walk() method