BUG: off-by-one when doing network test repeats

Imagine num_runs is two, then runs will take on the values [0, 1] and runs <
num_uns will always be False. Hence any genuine Exception the code might raise
will be silently ignored and just printed.
BUG/TST: fix (and skip) tests that have been failing unnoticed all along

The test is unstable and although this makes it work properly, no one knows how
long. Hence it was decided to skip this guy until further notice.

See also: #4427

Skip test_fred_nan and test_fred_parts, both of which have been failing silently for a while
Merge pull request #4485 'PR_fix_of-by-one-in-network-repeats'

Also added two skip tests for other fred tests in addition to @esc's
work.
BUG/TST: Fix failing FRED comparison tests and remove skips.
Merge pull request #4891 from TomAugspurger/fixfred3

BUG/TST: Fix failing FRED comparison tests and remove skips.
ENH: Series.str.extract returns regex matches more conveniently
Merge pull request #4696 from danielballan/str_extract

ENH: Series.str.extract returns regex matches more conveniently
DOC: warning about using numexpr > 2.1 as it has a backward incompatible change
     that affects PyTables < 3.0