defaults for which backends can run tests concurrently
warning police
disable codespeed integration by default

Enable it with `cabal configure -fcodespeed`

We can revisit this when codespeed starts behaving.
nofib: change default tests to Double and Int32
nofib: add flag to enable tests on all types
nofib: add tests for (nearly) all primitive operations

Currently missing, because we do not test Char and Bool type arrays:
 * ord, chr
 * logical operations
 * boolToInt