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/emitter.cpp

@@ -11,7 +11,7 @@ namespace YAML {
 class Binary;
 struct _Null;
 
-Emitter::Emitter() : m_pState(new EmitterState) {}
+Emitter::Emitter() : m_pState(new EmitterState), m_stream{} {}
 
 Emitter::Emitter(std::ostream& stream)
     : m_pState(new EmitterState), m_stream(stream) {}
@@ -906,4 +906,4 @@ Emitter& Emitter::Write(const Binary& binary) {
 
   return *this;
 }
-}
+}  // namespace YAML