http: when sniffer scans object members, it exports title of each member

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>
jsroot: i/o: reduce number of http requests when opening file; disable stamp parameter when not supported; reuse TDirectory streamer for TFile

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>
jsroot: elimante usage of global objects list via JSROOT.H() function; better handling of vertical separator

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>
jsroot: bug fix in file-selection interface

Signed-off-by: Bertrand Bellenot <bertrand.bellenot@cern.ch>
Implement Tf1::GetMaximum(Minimum)Stored returning the maximum/minimum  stored plotting values (same as TH1)
Use the new TF1 function GetMaximumStored take care of the TF1 maximum imposed by user.
- Implement GetNHists() to return the number of histograms in the stack.
Do not call Paint in TF1::GetHistogram(). Make a new member function TF1::DoCreateHistogram which is called by TF1::Paint and TF1::GetHistogram.