### Security
- Double-free in gdImagePngPtr(). (CVE-2017-6362)
- Buffer over-read into uninitialized memory. (CVE-2017-7890)
### Fixed
- Fix#109: XBM reading fails with printed error
- Fix#338: Fatal and normal libjpeg/ibpng errors not distinguishable
- Fix#357: 2.2.4: Segfault in test suite
- Fix#386: gdImageGrayScale() may produce colors
- Fix#406: webpng -i removes the transparent color
- Fix Coverity #155475: Failure to restore alphaBlendingFlag
- Fix Coverity #155476: potential resource leak
- Fix several build issues and test failures
- Fix and reenable optimized support for reading 1 bps TIFFs
73457b1982