search_path_restore no undoes tracing always

Didn't use to do so if search_path_check() failed
testing that messing with search path causes error
now exporting dummy funs
adding unitizer tests for zeroenv
ignored funs now compare robust to trace status

Used to compare just with identical, but that meant that
the library/attach/detach functions were not ignored
appropriately.  Now use @original slot of traced functions
whitespace cleanup
missing space typo
cleaned up formatting
capture tracing messages