schema plugin URI catalog / Fix when path contains space on windows

On master, having issue on installing it on windows when install folder contains space, I suggest the following change. I tried to remove as much as possible replacements made in different places and properly handle spaces when necessary.

Note : I was wondering if we could also add a cache to the resolver so we don't really go to all this (check if resolved, check if file exists) each time an XSL is used (even when XSL caching is on). View or edit metadata trigger a resolution of more than 20 potentials plugins + some utility XSLTs, and I don't know if File.exists could represent a significant time or not ? The cache could be populated once and provide a clearCache method when a new resource is added to the catalog (eg. when adding a plugin).