1.0.33.14: improve UCS external formats
Fix a simple bug in the CHAR->UCS-2BE error case.
Fix error-handling UCS-2 cases, by actually being careful about using the
return values of the encoding-error/decoding-error octet functions, and by
using adjustable vectors. Include tests for this.
Implement UCS-4, as a straight-through 32-bit encoding of the char-code.
Move external-formats/ucs-2.lisp to external-formats/enc-ucs.lisp, and include
a comment header explaining the distinction in our terms between UCS and UTF
external formats.