update gems
use new methods to activate inplace editing

fixes #253
allow to set internal links in the linklist editor
remove unused page method
implement text editor based on string editor
update changelog
remove test data
improve diagram widget

+ allow multiple diagram widgets on one page
+ update diagram only if the diagram was changed, not on anything else
mediabrowser: add error page filter

fixes #214
Merge branch 'feature/update-cloud-connector' into develop

* feature/update-cloud-connector:
  mediabrowser: add error page filter
  improve diagram widget
  remove test data
  update changelog
  implement text editor based on string editor
  remove unused page method
  allow to set internal links in the linklist editor
  use new methods to activate inplace editing
  update gems