Web. http::outgoing::Response. Fix data flush.

IODefinitions. Rename 'isValidIoHandle' --> 'isValidIOHandle'.

Merge pull request oatpp#166 from oatpp/thread_safe_LazyStringMap

LazyStringMap. Synchronize for thread-safety.

Increase oatpp version to '0.19.10'

Update README.md

Increase API version to 0.19.8

Merge pull request oatpp#102 from oatpp/fix_coroutine_member_caller

Fix coroutine member caller

Update README.md

Merge pull request oatpp#68 from oatpp/full_duplex_mode_support_for_i…

…o-event-worker

Full duplex mode support for io event worker

better IO error handling