Don't allow the deletion of the last keymap

Closes #178

src/components/keymap/edit/keymap-edit.component.html

@@ -1,5 +1,5 @@
 <template [ngIf]="keymap$ | async">
-    <keymap-header [keymap]="keymap$ | async"></keymap-header>
+    <keymap-header [keymap]="keymap$ | async" [deletable]="deletable$ | async"></keymap-header>
     <svg-keyboard-wrap [keymap]="keymap$ | async"></svg-keyboard-wrap>
 </template>
 

src/components/keymap/edit/keymap-edit.component.ts

@@ -12,7 +12,7 @@ import { ConnectableObservable } from 'rxjs/observable/ConnectableObservable';
 
 import { Keymap } from '../../../config-serializer/config-items/Keymap';
 import { AppState } from '../../../store';
-import { getKeymap } from '../../../store/reducers/keymap';
+import { getKeymap, getKeymapEntities } from '../../../store/reducers/keymap';
 
 @Component({
     selector: 'keymap-edit',
@@ -24,6 +24,7 @@ import { getKeymap } from '../../../store/reducers/keymap';
 })
 export class KeymapEditComponent {
     private keymap$: Observable<Keymap>;
+    private deletable$: Observable<boolean>;
 
     constructor(
         private store: Store<AppState>,
@@ -37,5 +38,8 @@ export class KeymapEditComponent {
 
         this.keymap$ = keymapConnectable;
         keymapConnectable.connect();
+
+        this.deletable$ = store.let(getKeymapEntities())
+            .map((keymaps: Keymap[]) => keymaps.length > 1);
     }
 }

src/components/keymap/header/keymap-header.component.html

@@ -22,6 +22,7 @@
            (click)="setDefault()"
         ></i>
         <i class="glyphicon glyphicon-trash keymap__remove pull-right" title=""
+            *ngIf="deletable"
            data-toggle="tooltip"
            data-placement="left"
            data-original-title="Remove keymap"

src/components/keymap/header/keymap-header.component.ts

@@ -15,6 +15,8 @@ import { KeymapActions } from '../../../store/actions';
 })
 export class KeymapHeaderComponent implements OnChanges {
     @Input() keymap: Keymap;
+    @Input() deletable: boolean;
+
     @ViewChild('name') keymapName: ElementRef;
     @ViewChild('abbr') keymapAbbr: ElementRef;