Remove alpha-flatten in default ImageMagick options, seems to break o…

…n many platforms (deb7/rhel)

core/src/plugins/editor.imagick/manifest.xml

@@ -11,7 +11,7 @@
 		<global_param name="IMAGE_MAGICK_CONVERT" type="string" label="CONF_MESSAGE[Convert Path]" description="CONF_MESSAGE[Full path on the server to the 'convert' binary]" default="/usr/bin/convert" mandatory="true"/>
 		<global_param name="IM_THUMB_QUALITY" type="string" label="CONF_MESSAGE[Thumbs Quality]" description="CONF_MESSAGE[Quality used for generating the thumbnails]" default="65"/>
 		<global_param name="IM_VIEWER_QUALITY" type="string" label="CONF_MESSAGE[Viewer Quality]" description="CONF_MESSAGE[Quality used for generation the high scale images]" default="90"/>
-        <global_param name="IM_CUSTOM_OPTIONS" type="string" label="CONF_MESSAGE[IMagick Options]" description="CONF_MESSAGE[You can add any Image Magick options you want here]" default="-alpha flatten -strip"/>
+        <global_param name="IM_CUSTOM_OPTIONS" type="string" label="CONF_MESSAGE[IMagick Options]" description="CONF_MESSAGE[You can add any Image Magick options you want here]" default="-strip"/>
         <global_param name="ADDITIONAL_ENV_PATH" type="string" label="CONF_MESSAGE[Environment Path]" description="CONF_MESSAGE[Additional path to put in the environment PATH variable before calling the command. Can be necessary for Ghostscript on Mac for example.]" default=""/>
 		<global_param name="ONTHEFLY_THRESHOLD" type="integer" label="CONF_MESSAGE[Pregeneration Threshold]" description="CONF_MESSAGE[Threshold (in MegaByte) under which the pages are all generated when opening the document, and over which pages are generated on-demand only]" default="5"/>
 		<global_param name="UNOCONV" type="string" label="CONF_MESSAGE[Unoconv Path]" description="CONF_MESSAGE[Full path on the server to the 'unoconv' binary (see docs)]" default="" mandatory="false"/>