Merge pull request #711 from jimis/3.3.x

Fix a crash happening rarely when exiting serverd
Pre-release version bump
Post-release version bump
Implement random calling of optimized OpenDB with a possible optional env var
Merge pull request #748 from jeffali/quickfix/alt0.33x2

Implement random calling of optimized OpenDB with a possible optional env var
Pre-release version bump
Post-release version bump
Fix: control of tokyocabinet optimization through env variables

First change: makes sure that threshold is correctly set
second:       threshold = 0 means "no optimization at all", completely skip the optimization process in such case
Merge pull request #749 from awsiv/fixoptimization_control

Fix: control of tokyocabinet optimization through env variables
Pre-release version bump
Post-release version bump
Increase polling interval to 10 ms from 10 us.

Else it is way too frequent and on old kernels we end up waiting minutes
instead of 1 second.