Avoid overflow in BackOffDelay and CombineDelay

#30

Export default configuration & MaxDelay option

contains

• #27
• #28

Support random jitter combined with other delay options.

PR: #26

Allocated length of `errorLog` should be 1 and not config.attempts if `lastErrorOnly` is set to true in the config

issue: #23
PR: #22

retryIf should be called before onRetry

retryIf should be called before onRetry #21

ability to mark error as unrecoverable

Add an ability to mark error as unrecoverable #18 and Fix missing delay before second attempt #19

Custom retry function

PR: #16
issue: #15

Added last error return from the retry function

more about in PR #14 (or ticket #13)

Allow to configure fixed or back off delay

more about in PR #12

Remove Units function

argument of retry.Delay is final delay (no multiplication by retry.Units anymore)

function retry.Units are removed

more about this breaking change #7