Implement kern_fs_path()

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>
shell: Print current working directory in prompt

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>
Add optional allocation tracing output to slab for finding memory leaks

Add a Kconfig option CONFIG_SLAB_TRACING which prints out a message on the
debug console on every allocation and free giving the address/function at
which the allocation/free call took place, and a script which takes a
kernel log with this output and uses it to create a list of all allocations
made which have not been freed by the time the log finishes. This can be
used to find memory leaks.

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>
Free region name in vm_region_destroy()

Signed-off-by: Alex Smith <alex@alex-smith.me.uk>