The different overloads of `RooAbsRealLValue::inRange()` implemented
different tolerances when checking if a value `x` falls inside a
specific range. Some overloads checked if the interval
`[x - 1e-6, x + 1e6]` is overlapping with the range, an other overload
checked if the interval `[x - 1e-8*x, x + 1e8*x]` is overlapping.

It's better is this is done consistently and predictably so this commit
suggests to leave out these epsilon margins that were never documented.
For backwards compatibility, one can set a custom relative or absolute
epsilon via the `RooNumber` interface.