[RFAv3 0/3] Implement 'set print frame-info|frame-arguments

[Philippe Waroquiers <philippe dot waroquiers at skynet dot be>]

When printing big stacktraces having a lot of functions with a lot of
arguments, it can be handy to see a lot less information in the
printed frames.

With the new settings, it is possible to have backtraces such as:
  (gdb) bt
  #0  break_me ()
  #1  call_me (...)
  #2  main ()
  (gdb)

that are only showing the level, the function name and the presence of
arguments.

This is the version V3 of the patch series.

Compared to V2, the changes are:
* Handles the comments of Tom:
   * Avoid leak in the py-framefilter.c code.
   * Ensure backtrace frame information printed does not depend on
     the presence of filters and/or of the -no-filters option.
* Reworked 'set print frame-info' to use the new -OPT option framework.
  A.o., it means that backtrace has a new option -frame-info to
  override the 'set print frame-info' settings.
* Updated the tests accordingly.
* The documentation and NEWS are also updated accordingly.

Compared to V1, the changes are:
* Handled the comment of Andreas Schwab : do not abbreviate words
  in 'set print fram-info' values, and use dash instead of underscore.
* Handled the comment of Tom about updating py-framefilter.c
  + updated py-framefilter.exp to test the new setting with python
  frame filter.
* Handled the comments of Eli about the documentation and NEWS.