Switch the bundled mincho font from a Source Han Serif JP subset to a
subset of IPA Mincho, which has monospace ASCII glyphs.
IPA Mincho's hhea ascent/descent already match its OS/2 typo metrics, so
adjust_metrics.py is no longer needed. However, IPA Mincho is distributed
under the IPA Font License v1.0, under which a subset is a "Derived
Program"; Article 3.1(4) forbids the derived font's name from containing
the licensed program's name ("IPA"). Add rename_font.py to rewrite the
name table accordingly, and replace licenses/mincho.txt with the IPA Font
License.
Graymerca uses JPEG images for map tiles, which suffers from color
bleeding due to chroma upsampling in the JPEG decoder.
Since stb_image cannot disable the bilinear upsampling filter, this
switches the JPEG decoder to NanoJPEG.
Fixes#67.
kichikuou