Add epanet input schema

sql/section_create/7.valves.sql

@@ -0,0 +1,14 @@
+-- [VALVES]
+
+CREATE TYPE VALVES_TYPE AS ENUM ('PRV', 'PSV', 'PBV', 'FCV', 'TCV', 'GPV');
+
+CREATE TABLE VALVES
+(
+  ID VARCHAR(32) PRIMARY KEY REFERENCES _LINK(ID)
+, Node1 VARCHAR(32) REFERENCES _NODE(ID) NOT NULL
+, Node2 VARCHAR(32) REFERENCES _NODE(ID) NOT NULL
+, Diameter NUMERIC NOT NULL
+, Type VALVES_TYPE NOT NULL
+, Setting NUMERIC NOT NULL
+, MinorLoss NUMERIC NOT NULL
+);