title: install qrencoder gem on osx for ruby on rails project
body: <p>I am trying to install the qrencoder gem on my mac osx 10.7.4 to use in a ruby on rails project.</p>
  
  <p>When I try gem install qrencoder here is what I get:</p>
  
  <p><code>ERROR:  Error installing qrencoder:
      ERROR: Failed to build gem native extension.
      /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb
      checking for qrencode.h... yes
      checking for QRinput_new() in -lqrencode... no
      *** extconf.rb failed ***
      Could not create Makefile due to some reason, probably lack of
      necessary libraries and/or headers.  Check the mkmf.log file for more
      details.  You may need configuration options.</code></p>
  
  <p>The mkmf.log file does not say anything other than the above.
  I have qrencode-3.3.0 installed ok with brew but the gem install fails: any idea ?</p>
  
  <p>when I type qrencode, here is what I get:</p>
  
  <p>"dyld: Library not loaded: /usr/local/lib/libqrencode.3.dylib
    Referenced from: /usr/local/bin/qrencode
    Reason: Incompatible library version: qrencode requires version 7.0.0 or later, but libqrencode.3.dylib provides version 5.0.0
  Trace/BPT trap: 5"</p>