Remember & Show Project filename

[gfwilliams]

It can get confusing when the IDE randomly appears with code that was saved on some other computer.

When loading/saving files it'd be nice if we could get the filename (not sure how possible this is on Chrome Web Apps vs web pages) and then save it in the IDE's settings along with the code itself.

The IDE could then show this so it'd be more obvious what code actually was.

(suggested by @IrregularShed)

[gfwilliams]

Load/save code is here: https://github.com/espruino/EspruinoWebIDE/blob/gh-pages/js/core/file.js#L132

It looks unlikely that the online IDE will be able to get a filename for saved files, but it should be ok for the Chrome app (for as long as those last :/) or NW.js (which uses the same API)