(CLI) Add -rose:keep_going commandline option

This commandline option is similar to GNU Make's --keep-going
option, except it will never fail (assuming the input code
is valid).

The point of this option is to provide a failover mechanism for
ROSE to completely compile large applications, even if some
of the files fail within the internal processings of ROSE.

If any internal ROSE errors occur, ROSE will simply pass the
original input file to the backend compiler. This also includes
the case where ROSE processes a file without failure, but the
unparsed file is actually invalid:

1) Parse the java source file.
   If it fails, use the original source code and move to step 3.
2) Unparse the java source file.
   If it fails, use the original source code and move to step 3.
3) Compile the resulting source file.
   If it fails and this was an unparsed version of the source file,
   use the original source file and repeat step 3.
4) If backend compilation fails, do not honor the "-rose:keep_going"
   option.

In order to use this option, ROSE must be configured to disable
assertions:

  $ CXXFLAGS="-DNDEBUG" $ROSE/configure ...

With assertions disabled, ROSE can run continuously, rather than
halting or aborting, and thereby terminating the program execution.
Instead, we throw and catch exceptions, or detect hardware signals
like SIGABRT (abort) and SIGSEGV (segmentation fault).

Conflicts:

	src/frontend/SageIII/sage_support/cmdline.h