Partially solving issue 1788: "Crashing during processing of queue"

It also correct a bug of wrong image orientation (was wrong in the File Browser while good in the Editor tab)

This patch also introduce several speed optimizations like:
   - switch between File Browser and Editor tab in Single Editor mode
   - asynchronous computation of the Batch Queue's thumbnails
   - quick start of RT even with a huge queue
   - less GUI overhead when applying a profile to multiple thumbs in the File Browser

rtgui/cachemanager.h

@@ -24,6 +24,7 @@
 #include <glibmm.h>
 #include "thumbnail.h"
 #include <cstdio>
+#include "../rtengine/procparams.h"
 
 class Thumbnail;
 
@@ -45,7 +46,7 @@ class CacheManager {
 		static CacheManager* getInstance(void);
 
         void        init        ();
-        Thumbnail*  getEntry    (const Glib::ustring& fname);
+        Thumbnail*  getEntry    (const Glib::ustring& fname, const rtengine::procparams::ProcParams *pparams=NULL);
         void        deleteEntry (const Glib::ustring& fname);
         void        renameEntry (const std::string& oldfilename, const std::string& oldmd5, const std::string& newfilename);