sheetName encoding issue fix. Conversion of sheetNames to UTF-8.
Removed 'Global-like' variables StartRow, startCol, ColNames, RowNames, Borders, BorderColour as not needed.

Set writeData2 example 2 not run to keep R-check happy on package dependencies.

Introduce validateBorder function to allow/check/convert colours() and hex colour codes

Modified createStyle to take colours() as borderColour

** Moved write functions to seperate scripts
Wrapped up removing/replacing illegal XML characters in to functions.
Replaced writeData with writeData2