Add support for TableGroup (#22)

* Add support for TableGroup

Author: CJSantee

syntaxes/dbml.tmLanguage.json

@@ -60,7 +60,7 @@
     "structures": {
       "comment": "Main data structure tags",
       "name": "entity.name.type.dbml",
-      "match": "\\b([pP]roject|[tT]able|[rR]ef|[eE]num|[iI]ndexes|[nN]ote)\\b"
+      "match": "\\b([pP]roject|[tT]able([gG]roup)?|[rR]ef|[eE]num|[iI]ndexes|[nN]ote)\\b"
     },
     "keywords": {
       "name": "keyword.dbml",

test/mysql.dbml

@@ -39,6 +39,11 @@ Table "orders" {
   "created_at" varchar(255) [note: 'When order created']
 }
 
+TableGroup "order" [note: "Tables related to orders"] {
+  "orders"
+  "order_items"
+}
+
 Table "products" {
   "id" int [pk]
   "name" varchar(255)

test/postgres.dbml

@@ -39,6 +39,11 @@ Table "orders" {
   "created_at" varchar [note: 'When order created']
 }
 
+TableGroup "order" [note: "Tables related to orders"] {
+  "orders"
+  "order_items"
+}
+
 Table "products" {
   "id" int [pk]
   "name" varchar

test/test.dbml

@@ -98,3 +98,9 @@ Table products {
 }
 
 Ref: products.merchant_id > merchants.id // many-to-one
+
+// TableGroups: You can combine multiple tables in a TableGroup
+TableGroup order {
+  orders
+  order_items
+}