- add additional migration files

- add seeder for collections
- coverage x_min, x_max, y_min, y_max
- SitelinkController db-independent

database/migrations/2019_09_02_090936_create_coverage_table.php

@@ -0,0 +1,50 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class CreateCoverageTable extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::create('coverage', function (Blueprint $table) {
+            $table->increments('id');
+
+            $table->integer('dataset_id')->unsigned();
+            $table->foreign('dataset_id')->references('id')->on('documents')
+            ->onUpdate('cascade')->onDelete('cascade');
+
+            $table->smallInteger('elevation_min')->nullable();
+            $table->smallInteger('elevation_max')->nullable();
+            $table->smallInteger('elevation_absolut')->nullable();
+            $table->smallInteger('depth_min')->nullable();
+            $table->smallInteger('depth_max')->nullable();
+            $table->smallInteger('depth_absolut')->nullable();
+            $table->dateTime('time_min')->nullable();
+            $table->dateTime('time_max')->nullable();
+            $table->dateTime('time_absolut')->nullable();
+            $table->float('x_min')->nullable();
+            $table->float('x_max')->nullable();
+            $table->float('y_min')->nullable();
+            $table->float('y_max')->nullable();
+
+            $table->timestamps();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::dropIfExists('coverage');
+    }
+}