bootstrapping with options as e.g. git branches now works as expected
switching the main configuration source as e.g.
autoproj switch-config branch=toolchain-2.3
now works as expected

New functionality:
amake accepts arguments i.e. if you are in a package you can do

amake --no-deps

to build only the current packages (amake alone would make sure that
all dependencies are uptodate)

added aup, which is the equivalent of amake for autoproj update, i.e.
doing

aup

in a subdirectory of a package will update that package and its
dependencies