Add color support to format string language

Format strings may now specify coloring.  The color options color_aux1
through color_aux8 are available for use in format strings.  To begin a
colored region, a specifier of the form '%#[num]%' is used, where [num]
is a number from 1-8, picking out the desired color.  Colored regions
are terminated with '%#0%'.

This is accomplished by adding escape codes to the output of
format_print(), which are interpreted in dump_print_buffer().  An
exception for the ASCII escape character is added to the uchar
functions.