One container for instantiations and different location

[Matthias Schoettle]

The two containers for Extended Aspects and Concern Reuses are not always nicely located for two reasons:

• They can overlap if one gets added something to
• When switching to a message view it hides the initial call of the message view.

I suggest the following changes to address this:

• Put both into one container that can be hidden together
• Put them on the bottom left or bottom right of the screen

[Cécile Camillieri]

References #377: single container for both instantiationsContainers. Default location is at bottom left of screen.

→ <<cset f26e366fd5f5>>

[Cécile Camillieri]

References #377: rename instantiationsPanel. Change tracing view default locatoin.

→ <<cset 4fca2abcba70>>