introducing SynCrossPlatformJSON unit for feature request [09ae8513eb]
  *  it is the first unit of Cross-Platform mORMot clients, running with FPC or Delphi NextGen compilers
  *  it is able to create schema-less objects or arrays, serialize and unserialize them as JSON, via a custom variant type, including late-binding to access the properties (just like our TDocVariant, but cross-platform)
  *  even if it is less optimized for speed and memory use than our TDocVariant, it is already much faster and using less resource than DBXJSON and XSuperObject (which are the only cross-platform JSON solutions we know about yet for Delphi), also faster than SuperObject under Windows - of course, dwsJSON is faster than this unit (but this latest is not cross platform), and FPC ready
  *  code is simple to follow and should be easy to maintain
  *  we will add