Chore: Renamed the Ledger Table to Account

Chore: Renamed the Ledger Model to Account
Chore: Renamed LedgerType to AccountType
Chore: Renamed all properties of Account table to lowercase with underscores

Feature: Starred Accounts and their entries do not delete during a rebase.
Info: Starred Vouchers still delete. They can be starred, but have no effect.

overlord/src/app/receipt/receipt.component.css

@@ -34,3 +34,11 @@
 mat-form-field.mat-form-field {
   font-size: 1.25em;
 }
+
+.gold {
+  color: gold;
+}
+
+.pointer {
+  cursor: pointer;
+}

overlord/src/app/receipt/receipt.component.html

@@ -1,6 +1,10 @@
 <mat-card>
   <mat-card-title-group>
     <mat-card-title>Receipt</mat-card-title>
+    <mat-icon matSuffix (click)="voucher.isStarred = !voucher.isStarred" class="pointer"
+              [class.gold]="voucher.isStarred">
+      {{ voucher.isStarred ? 'star' : 'star_border' }}
+    </mat-icon>
   </mat-card-title-group>
   <mat-card-content>
     <form [formGroup]="form" fxLayout="column">