expanded README.md and added example graphics.

Graphviz (the dot program) also does not accept dashes, the only accepted special character is underline

replaced by dashes. Optimized target search loop a bit

If the target option is used: check for link compatibility between targets and only consider files that are link compatible with first target

not start with a slash, add it

prevent them from being placed too close to each other

suppressed

'skipdirs'

that a symlink exists

the leading directory delimiter

program termination when an executable with an invalid ELF header is
analyzed

1. Some libraries have type ELFOSABI_LINUX instead of ELFOSABI_SYSV and,
   thus, were considered to belong to a different OS. In consequence,
   they were not searched for exports to the ELFOSABI_SYSV objects.
   The fix was to overwrite their type with ELFOSABI_SYSV.

2. Undefined symbols have (at least here) length 0, but symbols with length 0
   were completely skipped. The fix was to only skip symbols with length 0 if
   they are not marked as undefined.

3. Some valid function symbols have (again at least here) type STT_LOOS and
   were skipped, since only STT_FUNC was accepted. The fix was to store
   STT_LOOS symbols also as valid functions.

4. Symbolic links of libraries were stored but not evaluated. The fix was to
   add targets of symbolic links to the list of libraries to be evaluated.

5. In the original version, all symbols were included irrespective of whether
   they are in use or not. This has sometimes led to rather confusing images.
   The fix was to only include exported symbols that are in use at least once.

6. When an entire root file system was evaluated, the number of links exceeded
   by far what Neo4j could handle. The fix was to add the command line option
   "-t" or "--target" that accepts a comma-separated list of binary objects to
   scan. It this option is given, all other binaries are skipped. For this
   functionality it was required to recursively resolve all dependencies of the
   given binaries and to add them to the list of included binaries.

7. Added more output formats: 'gexf' for Gephi, 'gv' for Graphviz and
   'text' for simple text output.