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/singledocparser.cpp

@@ -18,6 +18,7 @@ SingleDocParser::SingleDocParser(Scanner& scanner, const Directives& directives)
     : m_scanner(scanner),
       m_directives(directives),
       m_pCollectionStack(new CollectionStack),
+      m_anchors{},
       m_curAnchor(0) {}
 
 SingleDocParser::~SingleDocParser() {}
@@ -170,10 +171,10 @@ void SingleDocParser::HandleBlockSequence(EventHandler& eventHandler) {
 
     // check for null
     if (!m_scanner.empty()) {
-      const Token& token = m_scanner.peek();
-      if (token.type == Token::BLOCK_ENTRY ||
-          token.type == Token::BLOCK_SEQ_END) {
-        eventHandler.OnNull(token.mark, NullAnchor);
+      const Token& nextToken = m_scanner.peek();
+      if (nextToken.type == Token::BLOCK_ENTRY ||
+          nextToken.type == Token::BLOCK_SEQ_END) {
+        eventHandler.OnNull(nextToken.mark, NullAnchor);
         continue;
       }
     }