Implement trainer battles and various changes

Implement trainer battles; add dialogue functionality; add random session seed for predictable random results; remove capitalization from text; add full party heal after every 10 waves

src/ui/modifier-select-ui-handler.ts

@@ -188,7 +188,7 @@ export default class ModifierSelectUiHandler extends AwaitableUiHandler {
       ui.showText(this.options[this.cursor].modifierTypeOption.type.description);
     } else {
       this.cursorObj.setPosition((this.scene.game.canvas.width / 6) - 50, -60);
-      ui.showText('Transfer a held item from one POKéMON to another instead of selecting an item');
+      ui.showText('Transfer a held item from one Pokémon to another instead of selecting an item');
     }
 
     return ret;