This function removes AST escape sequences from a supplied string,
returning the resulting text as the function value. The behaviour
of this function can be controlled by invoking the
astEscapesastEscapes function,
which can be used to supress or enable the removal of escape
sequences by this function.
AST escape sequences are used by the PlotPlot class to modify the
appearance and position of sub-strings within a plotted text string.
See the "EscapeEscape" attribute for further information.