turn abis_nm_debugp_foh() into a macro

this will avoid printing 'abis_nm.c' as the filename in the log, which
is pretty useless during debugging.  We want to know where
abis_nm_debugp_foh() is being used from, not where it is implemented.
abis_nm: add parenthesis for new abis_nm_debugp_foh() macro

without this, we break e.g. the openbsc build...
vty/command.c: Cosmetic cleanup

this is just changing some of the code to reduce the way too high level
of indentation and thus improve readability.
VTY: don't show HIDDEN or DEPRECATED vty commands in ? completion

This hides HIDDEN or DEPRECATED commands from showing up when the
full list of commands is inquired with '?' at any given point in the
command tree.  Only if the hidden/deprecated command is already typed
in partially, then it will still tab-complete.
debian: Update the change log for a new package
Added a ring buffer log target to store the last N log messages.

The log target can be used via log alarms and show alarms.
Why? This feature was proposed/requested at
http://openbsc.osmocom.org/trac/wiki/Tasks/ErrorLogTarget
All messages use the same amount of space, prioritizing simplicity.