TODO:
  * najit, kde to zije, kdo to udrzuje
  * pripadne submitnout internacionalni patch
     * v tom pripade ho musis udelat pres binmode utf-8 a lc a ne prasit tr! ;-)
  * opravdu absolutni vaha na 4-gramech => vety ze tri slov maji 0

<code>
sub NormalizeText {
    my ($norm_text) = @_;

# language-independent part:
    $norm_text =~ s/<skipped>//g; # strip "skipped" tags
    $norm_text =~ s/-\n//g; # strip end-of-line hyphenation and join lines
    ...

# language-dependent part (assuming Western languages):
    $norm_text = " $norm_text ";
    $norm_text =~ tr/[A-Z]/[a-z]/ unless $preserve_case;
    # BEWARE! PRIDAL JSEM RUCNE !!!
    $norm_text =~ tr/ÁÉÍÓÚŮČĎĚŘŠŤŽ/áéíóúůčďěřšťž/ unless $preserve_case;
    # BEWARE! PRIDAL JSEM RUCNE !!!
</code>