Handle UTF-8 in character literals

Also handle `\x{hhh..}` in strings... Character literals has to be a single character, not composite.

+ tests (and the corresponding fix to the char literal pretty printer)

test/aeso_parser_tests.erl

@@ -63,7 +63,8 @@ simple_contracts_test_() ->
      %% Parse tests of example contracts
      [ {lists:concat(["Parse the ", Contract, " contract."]),
         fun() -> roundtrip_contract(Contract) end}
-        || Contract <- [counter, voting, all_syntax, '05_greeter', aeproof, multi_sig, simple_storage, fundme, dutch_auction] ]
+        || Contract <- [counter, voting, all_syntax, '05_greeter', aeproof,
+                        multi_sig, simple_storage, fundme, dutch_auction, utf8] ]
     }.
 
 parse_contract(Name) ->
@@ -85,7 +86,7 @@ parse_expr(Text) ->
 round_trip(Text) ->
     Contract  = parse_string(Text),
     Text1     = prettypr:format(aeso_pretty:decls(strip_stdlib(Contract))),
-    Contract1 = parse_string(Text1),
+    Contract1 = parse_string(aeso_scan:utf8_encode(Text1)),
     NoSrcLoc  = remove_line_numbers(Contract),
     NoSrcLoc1 = remove_line_numbers(Contract1),
     ?assertMatch(NoSrcLoc, diff(NoSrcLoc, NoSrcLoc1)).

test/contracts/utf8.aes

@@ -0,0 +1,21 @@
+contract UTF8 =
+  entrypoint f1() : char = '1'
+  entrypoint f2() : char = '+'
+  entrypoint f3() : char = 'd'
+  entrypoint f4() : char = 'X'
+  entrypoint f5() : char = 'å'
+  entrypoint f6() : char = 'Ä'
+  entrypoint f7() : char = 'æ'
+  entrypoint f8() : char = 'ë'
+  entrypoint f9() : char = 'ẻ'
+  entrypoint f10() : char = '\x27'
+  entrypoint f11() : char = '\x{2200}'
+  entrypoint f12() : char = '💩'
+  entrypoint f13() : char = '\n'
+
+
+
+  // entrypoint f13() : char = 'e̊'
+  // entrypoint f14() : char = '\Ì'
+
+  // '💩' vs. map('a,'b)