Add epanet input schema

sql/section_create/9.demands.sql

@@ -0,0 +1,9 @@
+-- [DEMANDS]
+
+CREATE TABLE DEMANDS
+(
+  Junction VARCHAR(32) REFERENCES JUNCTIONS(ID) NOT NULL
+, Demand NUMERIC NOT NULL
+, Pattern VARCHAR(32) REFERENCES _PATTERN(ID)
+, Category TEXT NOT NULL
+);