(SActivitySequencer): add new editor to display an activity stepper

What does this MR do?

The list of the activities are displayed in a toolbar, the buttons are enabled only if the activity can be launched (if all its parameters are present). The sequencer uses the data from the previously launched activity to create the current one.

Create a new ActivityLauncher configuration to simplify the launch of an activity sequencer.

Improve ExActivities sample to use ActivitySequencer configuration and add volume rendering activity

How to test it?

Launch ExActivities sample and play with it.

Data

sample.tar.bz2

Some results

Additional tests to run

Read the documentation and try to use this stepper in your application.

Associated Issues/Merge Requests

• Issues
  • Fixes #279 (closed)
• Merge requests
  • !225 (merged)
  • !207 (merged)
  • Sight/sight-doc!21