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/nodeevents.cpp

@@ -20,7 +20,7 @@ anchor_t NodeEvents::AliasManager::LookupAnchor(
 }
 
 NodeEvents::NodeEvents(const Node& node)
-    : m_pMemory(node.m_pMemory), m_root(node.m_pNode) {
+    : m_pMemory(node.m_pMemory), m_root(node.m_pNode), m_refCount{} {
   if (m_root)
     Setup(*m_root);
 }
@@ -98,4 +98,4 @@ bool NodeEvents::IsAliased(const detail::node& node) const {
   RefCount::const_iterator it = m_refCount.find(node.ref());
   return it != m_refCount.end() && it->second > 1;
 }
-}
+}  // namespace YAML