```
template-id not allowed for constructor/destructor in C++20
```

About (possibly) unused functions.

…ings

The function actually parses an unsigned integer.

```
warning: Rethrowing current exception with 'throw;', it seems there is no current
exception to rethrow. If there is no current exception this calls std::terminate().
```

Comment out unused & problematic code:
```
crengine/include/lvref.h:395:16: warning: Reference to temporary returned. [returnTempReference]
   return LVRef(NULL);
               ^
crengine/include/lvref.h:396:15: warning: Reference to temporary returned. [returnTempReference]
  return LVRef( new T( *_ptr ) );
```

```
warning: Value stored to 'pDiag' is never read [clang-analyzer-deadcode.DeadStores]
```

```
warning: Rethrowing current exception with 'throw;', it seems there is no current
exception to rethrow. If there is no current exception this calls std::terminate().
```