This patch add the ability for the user to set a label for a target.
This can be very useful when debugging targets with the same executables
in the same session.
Labels can be set either at the target creation in the command
interpreter or at any time using the SBAPI.
Target labels show up in the target list output, following the target
index, and they also allow the user to switch targets using them.
Signed-off-by: Med Ismail Bennani <firstname.lastname@example.org>