Add support for receiving track position with milliseconds

[GrumpyBear57]

Also moved the conversion of formatted timespan to seconds to a separate method that uses TimeSpan.Parse instead of custom math.

[kenkangxgwe]

This might not be needed if we can directly return a timestamp (number) representation of the Position/Duration. See #74

[GrumpyBear57]

This PR is over 2 years old at this point, and I'd completely forgotten about it. I haven't used Rainmeter for probably the same amount of time, so have no stake in this whatsoever anymore.

I'm sure there's better ways to do this than what I had originally proposed, however when contributing to open source software I don't like to break backwards compatibility for trivial changes that I figured I would be the only one to use, which is probably why I opted for this simplistic solution.

I'll leave this PR open purely for shits and giggles, but I wouldn't be surprised if it sat here for another 2 years without any activity.

[keifufu]

Almost 2 years later now, it's time for this project to be brought back up to speed. Not sure if this PR gets merged or if I end up implementing this in another way but something like this should be included in the next version!

Edit: This project can now be found here