* Next bunch of changes for Win64

 - Use different typedefs for (U)Longptr_t to prevent overload errors on Win32
 - First round of replacing (U)Long_t with (U)Longptr_t where applicable (mostly on core) and fix the following kind of warnings (leading to errors when truncating pointers)
   `warning C4311: 'type cast': pointer truncation from 'void *' to 'Long_t'`
   `warning C4312: 'type cast': conversion from 'Long_t' to 'void *' of greater size`

* Better fix for pointer formatting

* Fix compilation warnings

* Apply Philippe's suggestion

* Try to fix 32bit/64bit pointer formatting using %zx

* Try to fix a compilation warning

Try to fix the following warning on `ROOT-debian10-i386/cxx14`:
```
warning: format ‘%zx’ expects argument of type ‘size_t’, but argument 4 has type ‘Longptr_t’ {aka ‘long int’} [-Wformat=]
```