Chore: Changed the Section Printer from Menu Categories to Sale Categories. This is more logical, in the older software, there as no concept of sale categories so menu categories was used.

This should make the whole thing much easier to update and read.

bookie/src/app/core/section-printer.ts

@@ -1,13 +1,13 @@
-import { MenuCategory } from './menu-category';
 import { Printer } from './printer';
+import { SaleCategory } from './sale-category';
 
 export class SectionPrinter {
-  menuCategory: MenuCategory | null;
+  saleCategory: SaleCategory | null;
   printer: Printer | null;
   copies: number;
 
   public constructor(init?: Partial<SectionPrinter>) {
-    this.menuCategory = null;
+    this.saleCategory = null;
     this.printer = null;
     this.copies = 0;
     Object.assign(this, init);