"Buildables" depend on tech graph

* Modified buildable definitions and loader to use technologies from the
tech graph as dependencies instead of the old research system

* Modified planet-related views and functions accordingly

legacyworlds-server-data/db-structure/parts/030-data/090-buildables.sql

@@ -10,21 +10,26 @@
 -- "Buildables"
 --
 CREATE TABLE tech.buildables(
-	name_id			INT NOT NULL PRIMARY KEY ,
-	description_id	INT NOT NULL ,
-	cost			INT NOT NULL CHECK( cost > 0 ) ,
-	work			INT NOT NULL CHECK( work > 0 ) ,
-	upkeep			INT NOT NULL CHECK( upkeep >= 0 )
+	name_id				INT NOT NULL PRIMARY KEY ,
+	description_id		INT NOT NULL ,
+	technology_name_id	INT ,
+	cost				INT NOT NULL CHECK( cost > 0 ) ,
+	work				INT NOT NULL CHECK( work > 0 ) ,
+	upkeep				INT NOT NULL CHECK( upkeep >= 0 )
 );
 
 CREATE INDEX idx_buildables_description
 	ON tech.buildables (description_id);
+CREATE INDEX idx_buildables_technology
+	ON tech.buildables ( technology_name_id );
 
 ALTER TABLE tech.buildables
 	ADD CONSTRAINT fk_buildables_name
 		FOREIGN KEY (name_id) REFERENCES defs.strings ,
 	ADD CONSTRAINT fk_buildables_description
-		FOREIGN KEY (description_id) REFERENCES defs.strings;
+		FOREIGN KEY (description_id) REFERENCES defs.strings ,
+	ADD CONSTRAINT fk_buildables_technology
+		FOREIGN KEY (technology_name_id) REFERENCES defs.technologies;
 
 
 --