Font offsets

[neurolabusc]

One great feature of this tool is that it creates a json file with the font metrics. Even nicer, this is a json file with the same parameters as the output of Hiero (though Hiero does not use a tab delimited format not JSON). What makes this fantastic is that with a few lines of code changes (shader and json reading) one can upgrade from the sdf fonts of Hiero to the sharper msdf.

I did want to point out on discrepancy: the "xoffset" and "yoffset" values are a bit different from Hiero. Left to its own devices, the fonts generated by this tool are displaced vertically upward and horizontally rightward. In my experience, this was about 1/6th the value stored in the font "base" (xoffset = xoffset - (0.17*base);). I presume this is a difference in the output of Hiero vs msdfgen, but as an enhancement it might be nice to make it truly plug-and-play compatible. I realize there is some work in this, not sure if my 1/6th adjustment works for all font sizes and bitmap sizes.