*
 * Tcl_UtfBackslash --
 *
 *	Figure out how to handle a backslash sequence.
 *
 * Results:
 *	Stores the bytes represented by the backslash sequence in dst and
 *	returns the number of bytes written to dst. At most TCL_UTF_MAX bytes
 *	returns the number of bytes written to dst. At most 4 bytes
 *	are written to dst; dst must have been large enough to accept those
 *	bytes. If readPtr isn't NULL then it is filled in with a count of the
 *	number of bytes in the backslash sequence.
 *
 * Side effects:
 *	The maximum number of bytes it takes to represent a Unicode character
 *	in UTF-8 is guaranteed to be less than the number of bytes used to