Revert "Allow use of custom HTML (#545)"

This reverts commit dc605c1683.

lib/interfaces/appconfig.go

@@ -6,9 +6,9 @@ type AppConfig interface {
 	GetHeight() int
 	GetTitle() string
 	GetResizable() bool
-	GetHTML() string
+	GetDefaultHTML() string
 	GetDisableInspector() bool
 	GetColour() string
 	GetCSS() string
 	GetJS() string
-}
+}

lib/renderer/webview.go

@@ -58,7 +58,7 @@ func (w *WebView) Initialise(config interfaces.AppConfig, ipc interfaces.IPCMana
 		Height:    config.GetHeight(),
 		Title:     config.GetTitle(),
 		Resizable: config.GetResizable(),
-		URL:       config.GetHTML(),
+		URL:       config.GetDefaultHTML(),
 		Debug:     !config.GetDisableInspector(),
 		ExternalInvokeCallback: func(_ wv.WebView, message string) {
 			w.ipc.Dispatch(message, w.callback)