repair for `uri-decode`

Certain inputs could cause `uri-decode` to go into a loop.

Patch and supplied by Doug Williams.

Closes PR 14010
ds-store/alias: fix for Mac OS X 10.4
Fix rackunit test/check-exn signature
* Changed bibtex author parsing to handle missing author field.
* Changed cite in autobib to handle missing author field.
Added to _bitmask auto increment bit numbers

Now (_bitmask '(a b)) == (_bitmask '((a 1) b)) == (_bitmask '((a 1) (b 2))

Or (_bitmask '((a 8) b)) == (_bitmask '((a 8) (b 16)))