
* error messages:

    - send to stderr instead of stdout
    - for debug, possibility to have file name and line where error happens
    - variable number of args, for printing more information
    - possibility of extending error codes, so that application can have
      their own

* options:

    - function execute_sub_options could be used in place of
      execute_options 

* libs/misc/msg.c:

    - use function error_found instead of err_msg

* warning messages:

    - similar to error messages, but do not raise an error 

* Signal handling:

    - trap signal for knowing where (really) bad things happen

* apps/nbr/scan_nbr.c:

    - Synchronization when a bad ensemble is read
    - remove output of binary file, and use Matlab to read directly raw
      data 

* apps/nbr/scan_nav.c:

    - implement an NMEA scanning type in addition to TRANSECT. This should
      not be difficult, as TRANSECT navigation type reads NMEA messages.
      This new type would not be able to synchonize navigation data with
      pings. However, it could be useful for filtering out some messages
      and/or bad navigation data, and generating healthier navigation
      files.  
    - improve scan_nav_line writting and reading to make it more stable.
    - implement a filter on velocity data
 
* apps/nbr/load_.c:

    - could use a good part of gfidb routines instead of having them
      redefined here

* apps/nbr/process.c:

    - design loading process with a control of which data to load
    - improve detection of bad data
    - implement possibility to load velocity from GPS velocity data,
      and/or filtered data
    - implement bit_names for methods of flagging bad data

* option list:
    
    - Some option list have a bit (ULONG) for the value of code. Since the
      later is an int, one should verify that no overflow can take place.
