Add support for reading from OBS Studio

[kamperemu]

Closes #61

Tested on Windows and Linux.
I've also added some configuration options (although I'm not completely sure if some of them are even needed).

I'd like to mention that it is possible to make the obs thread keep trying to reconnect if connection is lost but it currently just stops owocr if it disconnects.

[kamperemu]

Also I don't know why but github is showing diffs where lines haven't been changed. This also seems to be a quirk of this commit 0aa11cc.

[bpwhelan]

Just some comments since I assume this is inspired by GSM. I can review this if desired (after line endings fix), but just some initial thoughts.

• Lossless PNG being default will lead to a very bad experience for many people who try this. I've gone down that road before, and it's really awfully slow compared to a good quality jpeg.
• Should clamp scaling for many reasons

1. Giving OBS w/h bigger than the source's dimensions probably does nothing.
2. Super low scaling will completely break OCR
3. Weird scaling numbers could lead to soft images, negatively impacting performance and ocr results.

• Could add an option to capture the preview instead, or even make it default? Not a good fit for GSM but could definitely fit and make sense in owocr.

[kamperemu]

@bpwhelan Thanks for the feedback. Yes, this is inspired by GSM. I'd really appreciate a review (after I fix the line endings of course).