Burndown Chart

- Implemented burndown.daily, which is functional, but has outstanding
  problems that need to be addressed:
    - Slow
    - Does not optimize output (i.e. contains /\S\s+$/)
    - Needs generalized helper functions to reduce the size of the handler

src/Date.h

@@ -97,6 +97,11 @@ public:
 
   time_t operator- (const Date&);
 
+  void operator-- ();    // Prefix
+  void operator-- (int); // Postfix
+  void operator++ ();    // Prefix
+  void operator++ (int); // Postfix
+
 private:
   bool isEpoch (const std::string&);
   bool isRelativeDate (const std::string&);