Removed obsolete stuff from b.
Better put these large functions in the cpp file.
ps: remove unused constant.
Use a stripped down iso for network boots.
Added pstree.
Better remove the messages from parent on channel invalidation.
Added the F_DISMSG command to fcntl to discard messages.
Fixed the overpaint-bug when switching between UIs.

This is mostly done by using F_DISMSG before the change. This way,
we ensure that no messages are still in flight for the old client
and thus no updates will be made for the old client when we've
already switched to the new one.
Additionally, we are a bit more careful with setting the active
client during that time.
Removed floating point stuff from kernel.

We can't use it there that easily because we would have to
save the user-state first and restore it afterwards. So, better
don't use it at all.
To ensure that we don't use it by accident in the future, I added
the -msoft-float option which results in a linker error if we
have floating point arithmetic.
For that reason, we had to move some stuff from basic into the
c library and some tests out of the kernel test into libctest.
Don't let the mmap test fail on readonly filesystems.

Instead, don't do it at all and do a test with a virtual file
in all cases so that we still test the writeback.