Option to read feed from local file

[Yutin9]

Hello, and thanks for the work on this fork.

Currently the only options for adding feeds are providing links to webpages or importing ompl files (that would link to webpages), as was the case with fluent reader.

As I'm not sure support for in app scripting is a planned feature, I have some personal scripts I use to convert webpage content to RSS readable format. and I'd like to be able provide the local file output of these to fluent flame reader, a file check that only accepts xml data would seem the most reasonable option there.

[CrystalSplitter]

As I'm not sure support for in app scripting is a planned feature

To my knowledge I can't see how we would get this to safely work security-wise, though I would like custom CSS eventually. But that's a long ways out. Lots of other bugs to fix.

a file check that only accepts xml data would seem the most reasonable option there.

If you mean like, "upload" a local file that is a .atom, a .rss or a .xml, then I think we want this anyways to improve our mocha unittests. But it's a bit ways out and I would more consider this an infra change rather than a feature.