doc: bumped version to 0.10.13. 

bugfix: fixed compatibility regressions on Win32. this regression had… … appeared in commit 012f316.

doc: bumped version to 0.10.12. 

doc: updated the copyright years. 

api: bumped version to 0.10.12. 

doc: we now work with nginx cores as new as 1.13.6. 

tests: added full GC cycle operations to avoid false positives in the… … "check leak" test mode.

bugfix: the ssl connections might be drained and reused prematurely w… …hen ssl_certificate_by_lua* or ssl_session_fetch_by_lua* were used. this might lead to segmentation faults under load. thanks guanglinlv for the report and the original patch in openresty#1162.

tests: fixed a test case that might fail due to timing errors. 

bumped version to 0.10.10.