Feature #415

- Added feature #415, which supports displaying just a single page of tasks,
  by specifying either 'limit:page' to a command, or 'report.xxx.limit:page'
  in a report specification (thanks to T. Charles Yun).
- Modified the 'next' report to only display a page, by default.

src/Context.h

@@ -55,6 +55,7 @@ public:
   void shadow ();                      // shadow file update
 
   int getWidth ();                     // determine terminal width
+  int getHeight ();                    // determine terminal height
 
   void header (const std::string&);    // Header message sink
   void footnote (const std::string&);  // Footnote message sink
@@ -93,7 +94,6 @@ public:
   std::vector <std::string> tagRemovals;
   Hooks                     hooks;
 
-private:
   std::vector <std::string> headers;
   std::vector <std::string> footnotes;
   std::vector <std::string> debugMessages;