This is a function that turns tab characters into spaces. This is not as easy as one might think because of the way that tab characters work. In a non-proportionally spaced text layout, text is positioned according to the number of spaces, which are regarded as being the width of a column. A tab character moves the insertion point to the next tab position. Tab positions are every eighth column.
I suspect that there is an easier way of doing it!- however this routine seems to work and it is fast enough for my purposes
