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

assets/sass/datatable.scss

@@ -23,7 +23,7 @@ section.content .overlay > .fas,
 section.content > .overlay,
 .box > .loading-img,
 .overlay-wrapper > .loading-img {
-    position: absolute;
+    position: fixed; /* see #1330 */
     top: 0;
     left: 0;
     width: 100%;

assets/sass/sidebar.scss

@@ -39,3 +39,13 @@
         }
     }
 }
+
+/* 
+Simplify focus detection, when using keyboard tab navigation
+Deactivated, as it looks weird when the link is clicked 
+*/
+/*
+.sidebar-menu > li > a:focus {
+    text-decoration: underline;
+}
+*/