[Reduction] #422: draw_trapezoid

Yup. From TH03 on, ZUN uses a different version of master.lib, containing more
features than the last official version 0.23 from May 1995. Given the relative
insignificance of the features in question, I presume that Amusement Makers
must have kept their own, improved fork of master.lib, rather than ZUN having
hacked master.lib on his own.

Anyway, that doesn't matter. In the end, we still have to reverse-engineer each
and every one of these changes, and some of the more complicated functions
won't even be reduced before the actual reverse-engineering step of this
project.

[Binary change] Order of 3 relocations in TH05's OP.EXE.
[Reduction] #423: grcg_polygon_c
[Reduction] #424: grcg_triangle
[Reduction] #425: grcg_settile_1line
[Reduction] #426: graph_200line

Yup. TH03's graphics layer is actually set to a resolution of 640x200 and
upscaled by the hardware, which gives the game its distinctive low-res look.