Significantly reduces size of includes in header files
One has to include json.hpp where it really used

* Add XZ projection

* Get XZ Projection to work for geometry and axis drawing.

Co-authored-by: Yang Hang <yanghang@chao-Lenovo-XiaoXin-300>

Like in RBrowser, all items in hierarchy addressed using vector<string>

Avoid multiple parsing of path as a string

Only when correspondent widget created, necessary library will be loaded

Prevent crash when geometry not configured

Verbosity can be filtered overall (a la gErrorIgnoreLevel) or per group
of logs. To manage their limits and avoid locking, introduce channel objects.
They also take care of channel name normalization ("RIO" vs "IO" vs "v7io" etc).

The test for "should the log entry be emitted" is intentionally not thread-safe,
and the streaming operators are evaluated only when needed. This dramatically
reduces the cost of
```
void func() {
   R__DEBUG_HERE(gFooLog) << "Entered func: " << expensiveFunc();
   ...
}
```
- and the downside of unsynchronized access to the log verbosity seems like a
fair price, in 2020.

Add a test!

Fix bug in endcap calo tower offset

Clarifies ownership of TAxis objects

* Create calo towers from collection.
* Handle CaloTowerCollection model changes
* Pass and store extra selection information from streamed selection record
* Draw partially selected towers in Calo3DControl.DrawForSelection.
* Stream extra selection informantion also for implied selected
* Stream fraction parameter of selected cell in REveCalo3D
* Print all selected item indices in highlight tooltip
* Introduce external CaloData selector
* Implement REveCaloData selector
* Use std::unique_ptr for REveCalOData selector instead of plain pointer.
* Use dynamic cast instead of static cast in REveCaloData::ProcessSelection
* Use override instead of virtual for derived selector functions
* Reload ui5 table content on new event (changes in REveDataTable)
* Use emplace_bank instead of push_back in CellSelectionChangedInternal
* Replace push_back with emplace_back
* add virtual destructor and member initializers in REveCaloData
* small fixes in JS and xml code

Co-authored-by: Sergey Linev <S.Linev@gsi.de>

It makes very difficult to export library with other namespace,
much easier just add simple if statement in two projects where they used

Move existing nlohmann/json.hpp include to builtin location
and use it by default. When builtin_nlohmannjson is OFF,
cmake tries to find it in default location.