Report errors from lexical and stream level in parser

Before, only the syntax level (parse_*) was able to set the error
string. This patch fixes the situation so that lexical (lex_*) and
stream (stream_*) levels can report detailed error messages.

Also, instead of 0, EOF is now returned by stream on error.

test/testdata/invalid

@@ -30,7 +30,7 @@ unexpected token near ','
 ["a
 ====
 1
-invalid token near '"a'
+unexpected newline near '"a'
 ========
 ["a"
 ====
@@ -50,12 +50,12 @@ string or '}' expected near ','
 {"
 ====
 1
-string or '}' expected near '"'
+unexpected newline near '"'
 ========
 {"a
 ====
 1
-string or '}' expected near '"a'
+unexpected newline near '"a'
 ========
 {"a"
 ====
@@ -75,7 +75,7 @@ unexpected token near end of file
 {"a":"a
 ====
 1
-invalid token near '"a'
+unexpected newline near '"a'
 ========
 {[
 ====
@@ -135,4 +135,4 @@ invalid token near '-0'
 ["	 <-- tab character"]
 ====
 1
-invalid token near '"'
+control character 0x9 near '"'