Add 1+, 1- and -1+, and improve `abs` in cptypes #387

Job	Run time
ci (tpb, ubuntu-22.04, --pb --threads --enable-libffi, test-some-fast)	30m 7s
ci (a6osx, macos-13)	20m 16s
ci (ta6osx, macos-13)	23m 51s
ci (arm64osx, macos-14)	9m 20s
ci (tarm64osx, macos-14)	13m 29s
ci (i3le, ubuntu-22.04)	12m 44s
ci (ti3le, ubuntu-22.04)	15m 52s
ci (a6le, ubuntu-22.04)	8m 58s
ci (ta6le, ubuntu-22.04, CFLAGS+=-std=gnu89)	11m 54s
ci (ta6le, ubuntu-22.04, reboot, -m=ta6le --force, re.boot SCHEME="chezscheme", test-some-fast)	8m 34s
ci (i3nt, windows-2022, vs)	11m 22s
ci (ti3nt, windows-2022, vs)	14m 55s
ci (a6nt, windows-2022, vs)	11m 16s
ci (ta6nt, windows-2022, vs)	15m 9s
ci (ta6nt, windows-2022, gcc, CFLAGS+=-std=gnu89)	12m 47s
ci (ta6le, ubuntu-22.04, test-more, more)	56m 47s
	4h 37m 21s

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