ASTERIXDB-1226: implement SQL++ core group-by semantics and syntatic sugars.

-Implmented SQL++ core group-by semantics;
-Implemented SQL++ group-by syntatic sugars for standard SQL;
-Added test cases;
-Fixed column alias rewriter;
-Fixed the variable scoping for joins.

Change-Id: I6e5477d5bf80114cfff49c8ecb163849ee55eba6
Reviewed-on: https://asterix-gerrit.ics.uci.edu/752
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
diff --git a/asterix-app/src/test/resources/parserts/queries_sqlpp/columnalias.sqlpp b/asterix-app/src/test/resources/parserts/queries_sqlpp/columnalias.sqlpp
index 746660c..72eb1d9 100644
--- a/asterix-app/src/test/resources/parserts/queries_sqlpp/columnalias.sqlpp
+++ b/asterix-app/src/test/resources/parserts/queries_sqlpp/columnalias.sqlpp
@@ -21,4 +21,4 @@
 GROUP BY root
 WITH u AS root
 HAVING root > 0
-ORDER BY u; 
\ No newline at end of file
+ORDER BY u;
\ No newline at end of file