Log Message:
Changes 6.7.6.6:
* Always unlock the semaphore before returning from the png codec, either
  by a "return" or png_error(); changed all Magick*Exception() calls
  after setjmp() to png_error() to ensure proper cleanup (reference
  http://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=16883).
* Fixed log known alpha*kernel normalization bug in morphology convolve.
* Pixel allocation for Pango is stride*rows not stride*columns.
* Set the image resolution for Postscript files with an embedded Photoshop
  profile.
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