any changes to the laod string is either caught, or makes a
change to the returned objects...
Add a few tests found by the fuzzing routines to make sure
they are continue to be detected even if fuzzing is turned off..
fixes caught, reading past end of list, set and dict... Various float
parameters now raise errors when invalid..
[git-p4: depot-paths = "//depot/python/pypasn1/main/": change = 1823]