Issue-165 Added support for f-strings (literal string interpolation https://www.python.org/dev/peps/pep-0498/)

Opcodes handled: FORMAT_VALUE, BUILD_STRING.
Added AST node classes for FormattedValue and JoinedStr.

pyc_string.h

@@ -31,7 +31,7 @@ private:
     std::string m_value;
 };
 
-void OutputString(PycRef<PycString> str, char prefix = 0,
-                  bool triple = false, FILE* F = pyc_output);
+void OutputString(PycRef<PycString> str, char prefix = 0, bool triple = false,
+    FILE* F = pyc_output, const char* parent_f_string_quote = nullptr);
 
 #endif