Get rid of false positive gcc warnings

Due to an old bug [1], gcc generates false positive while using
designated initializers. This patch suppresses this warnings while
using gcc.

[1] (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36446)
Fix and consolidate option -e, -l, and -w

In the current implementation it was confusion when and when not the
prefix PRE (option -e) was prepended to the log filename (Besides the
problem that the current logic was broken).

Now, the option -e is only for the dumpfile anymore. Moreover, the
option -l and -w are consolidated. Option -w has now an optional
argument for the filename.
flowgrind: make -w optional, as originally intended
Delete trailing spaces; Use tabs instead of spaces
We don't support Solaris
Doxygen: force line break
Fix doxygen warning
flowgrind_stop - clean up usage and option parsing

This patch cleans up the option parsing and usage. The usage and the error
messages displayed during the command line parsing are inspired by the one
from coreutils
flowgrindd - clean up usage and option parsing

This patch cleans up the option parsing and usage. The usage and the error
messages displayed during the command line parsing are inspired by the one
from coreutils
flowgrind - clean up usage and option parsing

This patch cleans up the option parsing and usage. The usage and the error
messages displayed during the command line parsing are inspired by the
coreutils

Flowgrind's argument parsing is still far away from being clean. Most of the
problems arise from shortcomings of getopt_long(). In a further refinement of
the option parser we should think of using another library. At a first glance
GNU's 'arg_parser' seems promising. Other possibilities are GNU's 'argp',
and the parser from git (which is used by perf for example), which are both
may not lightweight enough
Update (doxygen) comments
New flow option -I for one-way delay calculation

Revert patch 61b4096aea. Instead display delay calculation only if option
-I is given. Make the same with RTT calculation (option -A)
Typo in usage_trafgenopt()
Move option -G to the logical right place in switch statement
To avoid code duplication, 'progname' is no more static.

Instead a function set_progname() is defined, which set the program
name based on argv[0]
Make includes explicit
Doxygen doesn't parse static variables or functions in header files

Move all static variables and functions from the header files to the
source files
Update (doxygen) comments
Coding style
Update TODO