Improve pagination & limit URL parameter handling

server/ui-src/stores/pagination.js

@@ -3,6 +3,7 @@ import { reactive } from 'vue'
 export const pagination = reactive({
 	start: 0,	// pagination offset
 	limit: 50, 	// per page
+	defaultLimit: 50, // used to shorten URL's if current limit == defaultLimit
 	total: 0,  	// total results of current view / filter
 	count: 0, 	// number of messages currently displayed
 })