Add rows_where parameter to Initializing vertable (src/common/sql/pgrouting_topology.sql)

````
    BEGIN
       raise DEBUG 'initializing %',vertname;
       execute 'select * from pgr_getTableName('||quote_literal(vertname)||')' into naming;
       IF sname=naming.sname  AND vname=naming.tname  THEN
                  /* we are adding if before truncate vertable and drop geometry column */
		   IF rows_where = 'true' THEN
               execute 'TRUNCATE TABLE '||pgr_quote_ident(vertname)||' RESTART IDENTITY';
               execute 'SELECT DROPGEOMETRYCOLUMN('||quote_literal(sname)||','||quote_literal(vname)||','||quote_literal('the_geom')||')';
           END IF;
	   ELSE
           set client_min_messages  to warning;
       	   execute 'CREATE TABLE '||pgr_quote_ident(vertname)||' (id bigserial PRIMARY KEY,cnt integer,chk integer,ein integer,eout integer)';
       END IF;
           /* also adding before trying to add geometry column and create index */
	   IF rows_where = 'true' THEN
		   execute 'select addGeometryColumn('||quote_literal(sname)||','||quote_literal(vname)||','||
					quote_literal('the_geom')||','|| srid||', '||quote_literal('POINT')||', 2)';
		   execute 'CREATE INDEX '||quote_ident(vname||'_the_geom_idx')||' ON '||pgr_quote_ident(vertname)||'  USING GIST (the_geom)';
	   END IF;
       execute 'set client_min_messages  to '|| debuglevel;
       raise DEBUG  '  ------>OK'; 
    END; 
````