Log Message:
ImageMagick: update to 7.0.7.23.

2018-02-18  7.0.7-23 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.0-23, GIT revision 22969:c6b3a22b0:20180218.

2018-02-09  7.0.7-23 Dirk Lemstra <dirk@lem.....org>
  * Add support for reading the HEIC image format to the Windows build.

2018-01-23  7.0.7-23 Cristy  <quetzlzacatenango@image...>
  * Fixed numerous use of uninitialized values, integer overflow,
	  memory exceeded, and timeouts (credit to OSS Fuzz).
  * Add list-length policy to limit the maximum image sequence length.