Style 1-based line spacing

[ItMightBeKaraoke]

KBS spaces lines based on the font and size of the first style, but their algorithm is a bit mysterious. Currently, kbputils doesn't even attempt to calculate the right spacing, and just uses 19, which is the value for Arial 12 Bold, the default Style 1 font.

I've been looking into reverse-engineering the algorithm, but until then, another option is just to use hardcoded values for known fonts and warn if another font is in style 1.

[ItMightBeKaraoke]

v0.0.8 added some minimal support with an option that uses hardcoded font spacing values, but there's got to be a better way, so leaving this open.