massive cleanup

* consistent script descriptions
* consistent cmdline parameter parsing with Getopt::Std
* remove some commented out & unused code
* fix some issues reported by perlcritic
* better code formatting
* and much more...
consistent use of operators

- don't combine high- and low-precedence operators
use of !~ operator instead of !(... =~ ...)
refactoring - extract method
cleanup & refactoring
consistent logging

- using the '-v' option to enable verbose logging
- verbose logging only on STDERR
- each log message in a separate line
consistent use of force & stop options
cleanup & refactoring
refactoring - extract cmdline parsing into separate method
refactoring - using File::Basename to get the directory a script
refactoring - reduce code duplication
performance tuning - use pre-compiled regexes for critical words

* @critical_words are scanned for every sentence
* by pre-compiling the regexes they have to be compiled only once
  instead of for every sentence
restructuring from multiple Perl scripts to modules

* no more intermediate files are generated
* improved reusability
add perldoc
extract license rules into separate module
fix handling of abbreviations at the beginning of a line

- the code was not in sync with the comment
cleanup
consistent logging (continued)

- verbose logging only on STDERR
cleanup .dict files

- only comments & newlines
remove unused/unreachable levenshtein code