NodeModel:
Changed fieldNames of configVariable.
Changed KeyPathString type frim String into SettingModelString;
Implements default values for config vars;
Enabled execute Node without ebter into config Dialog;
Saving and loading settings in Model;
FileHelper:
Added method GetUniqueFile - Return path of first unique file with given filename;
Merge branch 'configFix' into dev
Removed some unused imports;