Support for parsing SRT data as a String instead of a File.

[MaxPower15]

I split parse into parse_string and parse_file. The parse method
chooses which to run based on the input.

This also uncomments the test for a Spanish language file with dubious
encoding. The encoding fallback chain seems like it fixes it.

[simonrepp]

Hey max,

Thanks a lot, accepting both strings and files for parsing is a nice addition to the package :)
I'm going to run some tests with the spanish subtitle file, i tried to timeshift it previously,
fixing the encoding problems myself in sublime, but no matter which way i tried, afterwards they would not
show in VLC (Windows+Ubuntu) or Movie Player (Ubuntu) despite parsing without errors and looking flawless to me
in a text editor ... Maybe that's fixed now, sure would be great, let's see ;)

[MaxPower15]

Hey, thanks for the quick merge!

Yeah, I'm not 100% sure the Spanish stuff is truly fixed. I just noticed that, before my commit, when I uncommented it, it threw a few errors with unknown characters in my terminal (I'm using iterm2 on Mac OSX). After my change, no errors. But correlation is not causation, and I didn't test it on a real video, so I can't be sure.

Side note: Thanks for starting this project. It's definitely saving me some time. :)

[simonrepp]

Quick followup on the tests i wanted to run: everything fine, your encoding fallback chain is working superbly!
(The problems I described earlier came from an overlooked flaw in my timeshift code :))