Mark only included files as potentially unused (#442)

* Mark only included files as potentially unused

* Update CHANGELOG

* Add test

test/aeso_compiler_tests.erl

@@ -69,6 +69,7 @@ simple_compile_test_() ->
     [ {"Testing warning messages",
        fun() ->
            #{ warnings := Warnings } = compile("warnings", [warn_all]),
+           #{ warnings := [] } = compile("warning_unused_include_no_include", [warn_all]),
            check_warnings(warnings(), Warnings)
        end} ] ++
     [].

test/contracts/warning_unused_include_no_include.aes

@@ -0,0 +1,5 @@
+namespace N =
+    function nconst() = 1
+
+main contract C =
+    entrypoint f() = N.nconst()