style: improve design and add logo

- show data icons in thumbnails in data list items
- add app logo
- fix various visibility issues

src/app/modules/data/list/data-list-item.component.ts

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2018, 2019 StApps
+ * Copyright (C) 2018-2021 StApps
  * This program is free software: you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the Free
  * Software Foundation, version 3.
@@ -12,37 +12,20 @@
  * You should have received a copy of the GNU General Public License along with
  * this program. If not, see <https://www.gnu.org/licenses/>.
  */
-import {Component, Input, OnInit} from '@angular/core';
+import {Component, Input} from '@angular/core';
 import {SCThings} from '@openstapps/core';
 
 /**
- * TODO
+ * Shows data items in lists such es search result
  */
 @Component({
   selector: 'stapps-data-list-item',
   styleUrls: ['data-list-item.scss'],
   templateUrl: 'data-list-item.html',
 })
-export class DataListItem implements OnInit {
+export class DataListItem {
   /**
-   * TODO
+   * An item to show
    */
   @Input() item: SCThings;
-
-  /**
-   * TODO
-   */
-  constructor() {
-    // noop
-    // this.item is not available yet
-  }
-
-  /**
-   * TODO
-   */
-  // tslint:disable-next-line:prefer-function-over-method
-  ngOnInit() {
-    // noop
-    // this.item is available now - the template is loaded and compiled
-  }
 }