* tests/atgeneral.m4: Import M4sh.
Adjust the differences on the names of the builtins (define etc.).
(AT_CASE): Remove, use m4_case.
(AT_SETUP): Don't use `AT_group_description', `$1' is OK.
* tests/atspecific.m4 (m4_for, m4_foreach): Remove, use those of
M4sugar.
* tests/m4sugar.at: Strengthen the quotation and adjust to the new
macro names.
* tests/m4sh.at: Ditto.
* tests/torture.at: Ditto.
* tests/base.at: Ditto.
* m4sh.m4: Import M4sugar.
* autoconf.m4: Don't import M4sugar, M4sh does.
