Add 1990/theorem/try.sh

This script shows not just theorem but the sorter and the Fibonacci
generator as well. For the sorter it reverses output of ls (redirected
to a file) and then shows how using sorter on it results in the same
output of ls (with no options specified). Of course if different ls
sorts output differently this could fail but I did not think of that
until after I wrote it.

1990/theorem/Makefile

@@ -42,7 +42,7 @@ CSILENCE= -Wno-deprecated-declarations -Wno-empty-body -Wno-error -Wno-unused-va
 	-Wno-implicit-function-declaration -Wno-incompatible-pointer-types \
 	-Wno-macro-redefined -Wno-parentheses -Wno-return-type -Wno-unused-parameter \
 	-Wno-empty-translation-unit -Wno-deprecated-non-prototype -Wno-int-conversion \
-	-Wno-strict-prototypes
+	-Wno-strict-prototypes -Wno-implicit-int
 
 # Common C compiler warning flags
 #