Implement activity partition

[mbats]

Activity partition are missing.
See : http://www.uml-diagrams.org/activity-diagrams.html

[mbats]

See branch compartments.

• It should be possible to create vertical or horizontal regions depending on where the user create the second region. If he creates the second region East or West form the first one we will expect horizontal stack for the regions, else if he creates it North or South, it will be a vertical stack of regions.
• There is also a small problem with the rounded corner of the container and the activity partitions that go over their container.

[mbats]

Related to ticket : https://support.jira.obeo.fr/browse/VP-573

[mPorhel]

"There is also a small problem with the rounded corner of the container and the activity partitions that go over their container."

On #376 you do not have this problem: I think you enabled the rounded corner and put the same corner size.

See 376 for ideas on the correction.

[mbats]

See Sirius bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=436359

[mPorhel]

See https://bugs.eclipse.org/bugs/show_bug.cgi?id=470770 for the rounded corner issue. If the compartment mapping does not have a style with rounded corner, Sirius should draw the bottom corner of the last (vertical stack, first and last for horizontal stack) as rounded.

[mPorhel]

It should be possible to create vertical or horizontal regions depending on where the user create the
second region. If he creates the second region East or West form the first one we will expect horizontal
stack for the regions, else if he creates it North or South, it will be a vertical stack of regions.

The children presentation attribute is set on the region container mapping (and not on the style).
If you want to used different mapping regarding the location of the second compartment creation click, your tool might have to put some information in the model to let Sirius choose the good mapping. An other idea would be to improve the style customization mecanism to allow mapping customization as well.