termcol: distinguish 2C0x and analog ppu

Rename 7-bit digital version and create an analog variant based on NTSC
values, generated by <http://drag.wootest.net/misc/palgen.html> with sRGB
colorimetry and tuned (hue=0, sat=1, bri=.05, con=1, gam=1) to appear
similar to other (overly saturated) versions.