Check_MK Werk 2175: Added icon uploader, unified icon selection

ID: 2175 Title: Added icon uploader, unified icon selection Component: Multisite Level: 2 Class: New Feature Version: 1.2.7i1 Check_MK makes use of icons in views and dashboards, but it is also possible to add a custom icon to hosts or services for e.g. showing up the type of the device in a graphical way. This version also adds the option to register custom icons and actions to host and services. This change unifies the handling of icons used in such places. We implemented an icon selector which is used everywhere were you can select an icon. This icon selector groups the icons together in categories for more comfortable selection. We added an icon upload mechanism which gives you the option to manage your custom icons using WATO. You can find it in the top level navigation of WATO. All icons are now loaded from a fixed location, in OMD environments this is <tt>share/check_mk/web/htdocs/images/icons</tt> for the icons distributed by us and <tt>local/share/check_mk/web/htdocs/images/icons</tt> for your custom icons. Implementation detail: The category of an icon is saved directly in the icon image. It is stored in the PNG comment metadata.