adds strip option
makes stripping mandatory and ignores case

The stripping introduced in the last commit is now done automatically. Hence
the option --strip is removed. Still, a warning is issued if characters other
than [acgtACGT] were contained in the input. Also the case of the input is now
being ignored.
changes names to be printed left adjusted
fixes result for identical sequences
improves output

Now the default values for all parameters are printed on --help.
adds acknowledgements
fixes acknowledgements
fixes NaN result for nearly identical sequences
fixes low precision of printed results

If the distance matrix contains values smaller than 0.001
we now use scientific notation for the output to increase the
presicion.
Merge branch 'master' into autoconf
removes missing file
improves readme
adds missing to gitignore