hyphen-used-as-minus-sign in qr.1

Lintian complains:
"This manual page seems to contain a hyphen where a minus sign was
intended. By default, "-" chars are interpreted as hyphens (U+2010) by
groff, not as minus signs (U+002D). Since options to programs use minus
signs (U+002D), this means for example in UTF-8 locales that you cannot
cut and paste options, nor search for them easily. The Debian groff
package currently forces "-" to be interpreted as a minus sign due to
the number of manual pages with this problem, but this is a
Debian-specific modification and hopefully eventually can be removed."
Merge pull request #45 from ckorn/patch-1

Fix hyphens in man documentation