improved invoices with new renderer (#306)

* added docx renderer and demo template
* added csv renderer and demo template
* added xlsx renderer and demo template
* added ods renderer and demo template
* added user calculator
* added invoice documentation

.gitignore

@@ -7,11 +7,16 @@
 !bin/console
 /config/packages/local.yaml
 
-/var/data/kimai.sqlite
+templates/invoice/renderer/.~lock*
+
+/var/data/*.sqlite
+!/var/data/kimai_test.sqlite
 /var/coverage/
 /var/cache/*
 !var/cache/.gitkeep
 
+/var/invoices/*
+
 /var/log/*
 !var/log/.gitkeep