Fixed compile error with llvm libcxx

Pass c string to vtkWarningMacro instead.

Change-Id: I51d17cbe0dfa776ff3aad8d8a858590f64137e61
Fix assert in vtkRAdapter

907df31 introduced a bug that would allow
nodeWeights->GetValue(...) to be called if parent is
-1, move this code into the protected if block.

Change-Id: I9838f59dbb8b571f75ac9eb38f33114f4de45eaf
Removed a bunch of empty destructors

Their declaration violates the 'rule of 3' and was
causing compiler warnings with clang's -Wdeprecated
in C++11.

Change-Id: I959d582deea4ceccc69684be32dccd3521f54807
Merge topic 'fix-radapter-parent-index' into master

43d4a38b Fix assert in vtkRAdapter
Merge topic 'rule-of-three' into master

9e42e0e1 Removed a bunch of empty destructors
Merge topic 'libcxx-error' into master

10280aa5 Fixed compile error with llvm libcxx