5.5.0

1. Introduce JSROOT.StoreJSON() function. It creates JSON code for the
   TCanvas with all drawn objects inside. Allows to store current canvas state
2. Support "item=img:file.png" parameter to insert images in existing layout (#151)
3. Support TTree drawing into TGraph (#153), thanks @cozzyd
4. Let configure "&toolbar=right" in URL to change position of tool buttons
5. Let configure "&divsize=500x400" in URL of size of main div element (default - full browser)
6. Implement "optstat1001" and "optfit101" draw options for histograms
7. Remove "autocol" options - standard "plc" should be used instead
8. Provide drawing of artificial "$legend" item - it creates TLegend for all primitives in pad
   Can be used when several histograms or several graphs superimposed
9. Let configure "&toolbar=vert" in URL to change orientation of tool buttons
10. Improve markers and error bars drawing for TH1/TProfile