Skip unicode tests if `iconv --version` fails
Add instructions for windows users
Iteration over ENV (singleton of EnvHash Dict) returned a SubString
instead of a ByteString.  E.g. isequal(ENV,ENV) threw an error.

Now fixed.
Fix Issue #5581
base/pkg/git.jl: don't shell out to find .git dir [fixes #4888]
Fix #5586
Tweak tar finding code again
sharedarray - exported sdata, indexpids, subtype changes
Use rand(UInt32) for small ranges.
Change unlucky random seed in testing Woodbury.