finish file I/O implementation

[lmccart]

Updated after work by @therewasaguy:

XML is the one thing that could really benefit from some more work. Currently, we can load it, but it's hard to do anything with it because there is not yet an XML object like there is in Processing. An XML object could be really useful in tandem with p5.dom. An XML to JSON converter could also be useful even though that wouldn't always translate. I'd like to work on XML in theory, but in reality I'm not sure when I will get a chance, so if anybody is inspired they should go for it (and maybe open up a new ticket?).

More stuff that isn't supported and might be worth adding:

• loadBytes() / saveBytes() --> actually spent a decent amount of time trying to figure this one out. Maybe this will help.
• beginRecord() / endRecord() --> save a PDF of the sketch
• beginRaw() / endRaw() --> could create a vector?

[lmccart]

correct me if I'm wrong, but I think we can close this general issue with the great work from @therewasaguy. the last remaining bits to resolve are discussed in these issues:
https://github.com/lmccart/p5.js/issues/326
https://github.com/lmccart/p5.js/issues/280

[therewasaguy]

Well, I didn't actually get to all of the file i/o methods listed in the original ticket. I tried to focus on what would be most relevant.

XML is the one thing I think could really benefit from some more work. Currently, we can load it, but it's hard to do anything with it because there is not yet an XML object like there is in Processing. An XML object could be really useful in tandem with p5.dom. An XML to JSON converter could also be useful even though that wouldn't always translate. I'd like to work on XML in theory, but in reality I'm not sure when I will get a chance, so if anybody is inspired they should go for it (and maybe open up a new ticket?).

More stuff I haven't gotten to but might be worth doing:

• loadBytes() / saveBytes() --> actually spent a decent amount of time trying to figure this one out. Maybe this will help.
• beginRecord() / endRecord() --> save a PDF of the sketch
• beginRaw() / endRaw() --> could create a vector?

Stuff I don't think makes sense for p5:

• createInput()
• createOutput()
• selectInput()
• createReader()
• selectFolder()
• open()

[lmccart]

oops sorry for jumping the gun. I'll update the issue to reflect the current status. if these are things you'd like to tackle at some point feel free to keep your name on this issue. otherwise go ahead and deassign yourself, thanks for all your work on this area!

[therewasaguy]

I may dive back in at some point, but I'll deassign myself for now in case somebody else is interested in working on it in the meantime.

[lmccart]

great, sounds good!

[shiffman]

A small note I think that it might make sense to include something like selectInput() as an easy path to handling some of the JS File API stuff (this tutorial is a nice start). Thanks for all your amazing work @therewasaguy!