* fixed some bugs revealed by Paul Dietz' test suite:
** POSITION on displaced vectors with non-zero displacement
returns the right answer.
+ ** (SIGNED-BYTE) is a valid type specifier for sequence creators.
changes in sbcl-0.8.15 relative to sbcl-0.8.14:
* incompatible change: SB-INT:*BEFORE-SAVE-INITIALIZATIONS* and