Apply formatting/style tweaks to comply with compile time diagnostics for g++ and clang++ (#686)

* Add compilation flags: -Wshadow -Weffc++ -pedantic -pedantic-errors
* Delete implicit copy & move constructors & assignment operators
  in classes with pointer data members.
* An exception to the above: Add default copy & move constructors &
  assignment operators for the Binary class.
* Convert boolean RegEx operators to binary operators.
* Initialize all members in all classes in ctors.
* Let default ctor delegate to the converting ctor in
  Binary and RegEx
* Don't change any tests except regex_test (as a result of the change
  to binary operators).

Note: https://bugzilla.redhat.com/show_bug.cgi?id=1544675 makes
-Weffc++ report a false positive in "include/yaml-cpp/node/impl.h".

src/collectionstack.h

@@ -7,8 +7,8 @@
 #pragma once
 #endif
 
-#include <stack>
 #include <cassert>
+#include <stack>
 
 namespace YAML {
 struct CollectionType {
@@ -17,6 +17,7 @@ struct CollectionType {
 
 class CollectionStack {
  public:
+  CollectionStack() : collectionStack{} {}
   CollectionType::value GetCurCollectionType() const {
     if (collectionStack.empty())
       return CollectionType::NoCollection;
@@ -35,6 +36,6 @@ class CollectionStack {
  private:
   std::stack<CollectionType::value> collectionStack;
 };
-}
+}  // namespace YAML
 
 #endif  // COLLECTIONSTACK_H_62B23520_7C8E_11DE_8A39_0800200C9A66