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/scanner.cpp

@@ -9,10 +9,15 @@
 namespace YAML {
 Scanner::Scanner(std::istream& in)
     : INPUT(in),
+      m_tokens{},
       m_startedStream(false),
       m_endedStream(false),
       m_simpleKeyAllowed(false),
-      m_canBeJSONFlow(false) {}
+      m_canBeJSONFlow(false),
+      m_simpleKeys{},
+      m_indents{},
+      m_indentRefs{},
+      m_flows{} {}
 
 Scanner::~Scanner() {}