fileParsedFunc = function (e, root, fullPath) {
            importManager.queue.splice(importManager.queue.indexOf(path), 1); // Remove the path from the queue

            var importedEqualsRoot = fullPath === importManager.rootFilename;
            if (importOptions.optional && e) {
                callback(null, {rules:[]}, false, null);
            }
            else {
                importManager.files[fullPath] = root;
                if (e && !importManager.error) { importManager.error = e; }
                callback(e, root, importedEqualsRoot, fullPath);
            }
        }
Add an import to be imported
@param path - the raw path
@param tryAppendLessExtension - whether to try appending the less extension (if the path has no extension)
@param currentFileInfo - the current file info (used for instance to work out relative paths)
@param importOptions - import options
@param callback - callback for when it is imported