Rewrite SQL++ functions.

-Maps SQL function names to internal names.
-Allows SQL++ builtin functions to be case-insensitive.
-Rewrites SQL-92 global aggregates.
-Refactors SQL++ AST visitors.
-Cleans up semantics of COLL_AGG and SQL-92 AGG.

Change-Id: Idb5a7c6780669b27065b0928bec7e4700cfb53a9
Reviewed-on: https://asterix-gerrit.ics.uci.edu/759
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
diff --git a/asterix-app/src/test/resources/optimizerts/queries_sqlpp/query-issue810-2.sqlpp b/asterix-app/src/test/resources/optimizerts/queries_sqlpp/query-issue810-2.sqlpp
index b2e4121..16655ff 100644
--- a/asterix-app/src/test/resources/optimizerts/queries_sqlpp/query-issue810-2.sqlpp
+++ b/asterix-app/src/test/resources/optimizerts/queries_sqlpp/query-issue810-2.sqlpp
@@ -51,7 +51,7 @@
 
 create  table LineItem(LineItemType) primary key l_orderkey,l_linenumber;
 
-select element {'l_returnflag':l_returnflag,'l_linestatus':l_linestatus,'count_cheaps':tpch.count(cheaps),'avg_expensive_discounts':tpch.avg(expensives),'sum_disc_prices':tpch.sum(disc_prices),'total_charges':tpch.sum(charges)}
+select element {'l_returnflag':l_returnflag,'l_linestatus':l_linestatus,'count_cheaps':tpch.coll_count(cheaps),'avg_expensive_discounts':tpch.coll_avg(expensives),'sum_disc_prices':tpch.coll_sum(disc_prices),'total_charges':tpch.coll_sum(charges)}
 from  LineItem as l
 where (l.l_shipdate <= '1998-09-02')
 /* +hash */