19.3 - Standard

Sanic 19.3 is a standard release based on the CalVer versioning adopted in 2018.

Changes:
#1502 Remove current_time prefetch
#1499 Add Route Resolution Benchmarking to Unit Test
#1497 Recognizes non-ASCII filenames in RFC 2231, and suport filename length is zero for multipart/form-data.
#1489 Added "databases" (documentation)
#1487 Remove deleted repo from extensions list
#1484 Enforce Datetime Type for Expires on Set-Cookie
#1483 Add sanic-zipkin to extensions list
#1482 Add stream support for bp.add_route()
#1481 Allow negative int/number in path
#1478 Upgrade setuptools version and use native docutils in doc build
#1472 Remove unwanted None check for repr in Request class
#1470 make Sanic.create_server return an asyncio.Server

Fixes:
#1516 Fix typo at the exception documentation
#1515 fix linter issue causing travis build failures (fix #1514)
#1510 fix typo in Asyncio example
#1501 Fix the auto_reloader to work when the executable was launched with a module
#1490 Fix python version in doc build
#1486 did you mean specific? (documentation typo)
#1477 Fix grammar in README.md
#1476 add Request.not_grouped_args, deprecation warning Request.raw_args deprecation idea discussion
#1464 Upgrade pytest, and fix caplog unit tests