Add epanet input schema

sql/section_create/4.tanks.sql

@@ -0,0 +1,16 @@
+-- [TANKS]
+
+CREATE TYPE TANKS_OVERFLOW AS ENUM ('YES', 'NO');
+
+CREATE TABLE TANKS
+(
+  ID VARCHAR(32) PRIMARY KEY REFERENCES _NODE(ID)
+, Elevation NUMERIC NOT NULL
+, InitLevel NUMERIC NOT NULL
+, MinLevel NUMERIC NOT NULL
+, MaxLevel NUMERIC NOT NULL
+, Diameter NUMERIC NOT NULL
+, MinVol NUMERIC NOT NULL
+, VolCurve VARCHAR(32) REFERENCES _CURVE(ID)
+, Overflow TANKS_OVERFLOW
+);