ENH: Slightly bigger patch:

ENH: Slightly bigger patch:
1. Getting toward full integration of JMR patch for writting dicom from scratch
2. Update Test to test part of this patch: CreateUniqueUID
3. File was not close properly in gdcmDict
4. Use of typedef is to be prefered when possible (gdcmDict.cxx)
5. Use of const ref instead of copy (speed issue)
6. Remove temporary (duplicate) string in TranslateToKey
7. Mark extremely dangerous code as such (gdcmDocument.cxx and AddEntry fallback case)
8. Do not repeat virtual in subclasses
9. Implemented in gdcm::Util two new function: GetIPAddress, and CreateUniqueUID