This port offers VIQR<->VISCII (RFC 1456) conversion and VISCII ctype-like
routines for Vietnamese text processing.  Of prime interest is the finite
state machine that reads 7-bit Viet-Net style Vietnamese and produces 8-bit
output.  Developers are encouraged to take advantage of these routines for
these reasons:

  - Parsing task is greatly simplified
  - Makes one's code easier to port from one character encoding to another
  - Ensures a consistent user interface across many software packages