Add file reader

[bminortx]

PLY filepath is currently hardcoded into the app. This is nice for proof-of-concept, but it would be preferable if there was a way to just select a PLY from the GUI itself.

[17100109]

Were you able to finally add your own .ply file?

[bminortx]

...I haven't worked on this project in a while, actually. But I feel like it would be a fairly straightforward affair. I'll try to get around to it sometime, just to round off this project.