silence most warnings under macOS

For macOS Apple clang version 15.0.0 (clang-1500.3.9.4)
compiler, we have silenced the warnings that can be silenced.

We also updated `.gitignore` for `2014/maffiodo2` and `1995/vanschnitz`.

1991/fine/Makefile

@@ -95,7 +95,7 @@ endif
 #
 ifeq "$(findstring $(GCC),${CC})" "$(GCC)"
 #
-CSILENCE+= -Wno-missing-parameter-type
+CSILENCE+= -Wno-missing-parameter-type -Wno-unknown-warning-option
 #
 #CWARN+=
 #