target

Let set text, xml, json, binary content types and content itself

std::string also capable to keep binary data without limitation.
Of course, c_str() makes no big sense, but anyway interpretation of
that data fully user-specific

If somebody uses THttpSniffer class before, code will be compiled and
running. 

If any subclass from TRootSniffer will be done, one should probably use
TRootSnifferFull as base class - depending if extra functionality like
sub-pads scannig is required

If provided with quotes, JSON members interpreted as string and cannot
be correctly used in the JSROOT

Full version of sniffer will be TRootSniffer and used by default.
Only in special situation TRootSnifferBase will be used, which does
not depend from histo, graph, gpad libraries

Now only full-functional sniffer can produce or parse XML files

Here will be placed the code, which depends from gpad, tree, image and
other libraries