Add to read TH3 object and override `getBin`, `getBinContent` and `getStats` functions for TH3.


git-svn-id: https://root.cern.ch/svn/root/branches/dev/cshen@48738 27541ba8-7e3a-0410-8455-c3a389f83636
Enable to open TH3 object and add to load required libraries.


git-svn-id: https://root.cern.ch/svn/root/branches/dev/cshen@48739 27541ba8-7e3a-0410-8455-c3a389f83636
Implement `drawHistogram3D` and `drawHistogram2D3D` functions.


git-svn-id: https://root.cern.ch/svn/root/branches/dev/cshen@48740 27541ba8-7e3a-0410-8455-c3a389f83636
Add `testTH3.root` file for testing load TH3 object.


git-svn-id: https://root.cern.ch/svn/root/branches/dev/cshen@48741 27541ba8-7e3a-0410-8455-c3a389f83636