Cycles: some warning fixes, cpu device task tweaks, avoid unnecessary

tonemap in non-viewport render, and some utility functions.

intern/cycles/util/util_path.cpp

@@ -27,6 +27,7 @@ OIIO_NAMESPACE_USING
 #define BOOST_FILESYSTEM_VERSION 2
 
 #include <boost/filesystem.hpp> 
+#include <boost/algorithm/string.hpp>
 
 CCL_NAMESPACE_BEGIN
 
@@ -60,6 +61,18 @@ string path_join(const string& dir, const string& file)
 	return (boost::filesystem::path(dir) / boost::filesystem::path(file)).string();
 }
 
+string path_escape(const string& path)
+{
+	string result = path;
+	boost::replace_all(result, " ", "\\ ");
+	return result;
+}
+
+bool path_exists(const string& path)
+{
+	return boost::filesystem::exists(path);
+}
+
 string path_files_md5_hash(const string& dir)
 {
 	/* computes md5 hash of all files in the directory */