(ExActivitiesQml): implement activities for Qml applications

What does this MR do?

Create a Qml sample to launch activities.

• Create base class for activity launcher and sequencer service to share the code between qml and qt services.
• Move qml style from guiQml to styleQml bundles
• improve AppManager to manage input parameters and to generate unique identifier

How to test it?

Set the cmake flag ENABLE_QML_APPLICATION to ON when you compile ExActivitiesQml (don't forget to remove if after that if you need to support the old API of activity launcher service)

• Launch ExActivitiesQml
• open a mask image (see sample.tar.bz2)
• click on Mesher button in the toolbar
  • generate one ore more mesh
• click on Display button in the toolbar
• play with the application

Data

sample.tar.bz2

Some results

Associated Issues/Merge Requests

• Issues

  • Refs #279 (closed)

• Merge requests

  • depends !225 (merged)