Allow dbname query parameter in URL conn string

fixes #69

config.go

@@ -426,7 +426,15 @@ func parseURLSettings(connString string) (map[string]string, error) {
 		settings["database"] = database
 	}
 
+	nameMap := map[string]string{
+		"dbname": "database",
+	}
+
 	for k, v := range url.Query() {
+		if k2, present := nameMap[k]; present {
+			k = k2
+		}
+
 		settings[k] = v[0]
 	}
 

config_test.go

@@ -227,6 +227,18 @@ func TestParseConfig(t *testing.T) {
 				RuntimeParams: map[string]string{},
 			},
 		},
+		{
+			name:       "database url dbname",
+			connString: "postgres://localhost/?dbname=foo&sslmode=disable",
+			config: &pgconn.Config{
+				User:          osUserName,
+				Host:          "localhost",
+				Port:          5432,
+				Database:      "foo",
+				TLSConfig:     nil,
+				RuntimeParams: map[string]string{},
+			},
+		},
 		{
 			name:       "database url postgresql protocol",
 			connString: "postgresql://jack@localhost:5432/mydb?sslmode=disable",