Code Cleanup

- Relocated the Table::getCharLength() from Johannes to text.cpp/characters()
  because it is a general-purpose function, and will be the start of the UTF8
  conversion of all text.cpp code.
- Added unit tests for characters().

src/Table.h

@@ -100,7 +100,6 @@ private:
            void calculateColumnWidths ();
            just getJustification (const int, const int);
            just getHeaderJustification (const int);
-           int getCharLength (const std::string&);
            const std::string formatHeader (const int, const int, const int);
            const std::string formatHeaderDashedUnderline (const int, const int, const int);
            void formatCell (const int, const int, const int, const int, const int, std::vector <std::string>&, std::string&);