docs: avoided using module() and also recommended the lua-releng tool to locate misuse of Lua globals.
docs: documented more limitations in the current implementation.
bugfix: we did not declare the "level" local variable of ngx_http_lua_ngx_log at the beginning of the code block. thanks Edwin Cleton for the report.
bumped version to 0.8.10.
Merge branch 'master' into websocket