* Update to go-org 1.3.2

Fix #12727

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix unit test

Signed-off-by: Andrew Thornton <art27@cantab.net>

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

* Update go-org to 0.1.9

What I did to generate this commit:

$ go get github.com/niklasfasching/go-org

* make vendor

* Rewrite markdown rendering to blackfriday v2.0

* Fix style

* Fix go mod with golang 1.13

* Fix blackfriday v2 import

* Inital orgmode renderer migration to go-org

* Vendor go-org dependency

* Ignore errors :/

* Update go-org to latest version

* Update test

* Fix go-org test

* Remove unneeded code

* Fix comments

* Fix markdown test

* Fix blackfriday regression rendering HTML block