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/tag.cpp

@@ -6,7 +6,8 @@
 #include "token.h"
 
 namespace YAML {
-Tag::Tag(const Token& token) : type(static_cast<TYPE>(token.data)) {
+Tag::Tag(const Token& token)
+    : type(static_cast<TYPE>(token.data)), handle{}, value{} {
   switch (type) {
     case VERBATIM:
       value = token.value;
@@ -46,4 +47,4 @@ const std::string Tag::Translate(const Directives& directives) {
   }
   throw std::runtime_error("yaml-cpp: internal error, bad tag type");
 }
-}
+}  // namespace YAML