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/emitterstate.h

@@ -145,7 +145,12 @@ class EmitterState {
 
   struct Group {
     explicit Group(GroupType::value type_)
-        : type(type_), indent(0), childCount(0), longKey(false) {}
+        : type(type_),
+          flowType{},
+          indent(0),
+          childCount(0),
+          longKey(false),
+          modifiedSettings{} {}
 
     GroupType::value type;
     FlowType::value flowType;
@@ -198,6 +203,6 @@ void EmitterState::_Set(Setting<T>& fmt, T value, FmtScope::value scope) {
       assert(false);
   }
 }
-}
+}  // namespace YAML
 
 #endif  // EMITTERSTATE_H_62B23520_7C8E_11DE_8A39_0800200C9A66