bugfix: option.robot was ignored and always true
feature/bugfix: add option.dest and use as output path

- using files[0] lead to error if this file was not in root but deeper directory
bugfix: option.robot was ignored and always true
feature/bugfix: add option.dest and use as output path

- using files[0] lead to error if this file was not in root but deeper directory
feature: add option to overwrite changefreq per file (file.data.changefreq)
cosmetical changes (code formatting, naming, simplify)
wip: enable globbing patterns for option.exclude

First tests are successful. But the problem remains, that all excluded files are listed in robots.txt.
Merge pull request #16 from hgoebl/develop

mixed: some new small features and bugfixes