experimental feature to run several commands using a single

dunecontrol call.

commands are given as a colon seperated list.

example:
dunecontrol --opts=optsfile autogen:configure:make
would do exactly the same as
dunecontrol --opts=optsfile all

This feature will change in the future, as it does not allow different
parameters for the different commands.


[[Imported from SVN: r5298]]