added project start and end date (#1303)

* added sortable js library
* activity in invoice is optional
* added javascript widget for paginated boxes
* fix activity dropdown for globals only
* added timesheet service to reduce code duplication
* use repository to query for teams in dropdowns
* added project validator
* validate project start and end against timesheet
* include begin and end in dynamic form requests for projects
* added timezone and language option to import flag, improve timesheet import speed
* deactivate cross-timezone filter
* add virtual fields to field order list
* composer update
* added param to ignore dates
* position loader icon fixed - fixes #1330
* permission problem when creating a new project - fixes #1340
* remove dev dependencies webserver and thanks bundle
* stop information leak (begin and end date) in duration mode - fixes #1307
* unify timesheet edit dialog for user and admins
* fix security issue, own rates exposed to unauthorized users in multi-update dialog

src/Invoice/Calculator/ActivityInvoiceCalculator.php

@@ -20,6 +20,10 @@ class ActivityInvoiceCalculator extends AbstractSumInvoiceCalculator implements
 {
     protected function calculateSumIdentifier(InvoiceItemInterface $invoiceItem): string
     {
+        if (null === $invoiceItem->getActivity()) {
+            throw new \Exception('Cannot work with invoice items that do not have an activity');
+        }
+
         if (null === $invoiceItem->getActivity()->getId()) {
             throw new \Exception('Cannot handle un-persisted activities');
         }