Address code style and quality issues (#203)

Cleaned up by clang-tidy 7.0.0.
Enabled checks:
  - boost-use-to-string
  - misc-uniqueptr-reset-release
  - modernize-deprecated-headers
  - modernize-make-shared
  - modernize-use-bool-literals
  - modernize-use-equals-delete
  - modernize-use-nullptr
  - modernize-use-override
  - performance-unnecessary-copy-initialization
  - readability-container-size-empty
  - readability-redundant-string-cstr
  - readability-static-definition-in-anonymous-namespace
  - readability-uniqueptr-delete-release

See http://releases.llvm.org/7.0.0/tools/clang/tools/extra/docs/clang-tidy/index.html for details.

RecoPixelVertexing/PixelTrackFitting/test/PixelTrackRiemannFit.cc

@@ -190,7 +190,7 @@ void test_helix_fit() {
     gen_par(4) = 10.;   // R (p_t)
     gen_par(5) = 1.;   // eta
     iteration = 1;
-    return_err = 1;
+    return_err = true;
     debug2 = 1;
 
     iteration *= 10;