Unique IDs to materials and media

Proposed solution to G4 issue reading media as discussed in #2913.

Index numbers are attached to Materials and Media, with the corresponding media to corresponding material only matching accidentally due to loading. Additionally Material and Media names normally match but not always. As we have seen FairRoot, CbmRoot and G4 have been interpreting material and media differently when overlaps of index numbers occurs. Each of these have sought the solution to shuffle index numbers when issued arose but because they do so differently this causes issues and causes materials/media to be swapped. This latest problem is highlighted by differences between G3 and G4 interpretation of media and is not seen by examining the material in root.

The proposed solution here, is to "uniquely" convert the name of the material/media into index (Int_t 4 billion unqiues) This is definitely cannot be achieved strictly, as an Int_t would only guarantee uniqueness for 4 ascii characters, for this reason uppercase and lowercase letters are treated identically and common symbols concatenated.