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/Entity/Timesheet.php

@@ -141,7 +141,7 @@ class Timesheet implements EntityWithMetaFields, InvoiceItemInterface
     /**
      * @var Tag[]|ArrayCollection
      *
-     * @ORM\ManyToMany(targetEntity="Tag", inversedBy="timesheets", cascade={"persist"})
+     * @ORM\ManyToMany(targetEntity="App\Entity\Tag", inversedBy="timesheets", cascade={"persist"})
      * @ORM\JoinTable(
      *  name="kimai2_timesheet_tags",
      *  joinColumns={