Change markdown rendering from blackfriday to goldmark (#9533)

* Move to goldmark

Markdown rendering moved from blackfriday to the goldmark.

Multiple subtle changes required to the goldmark extensions to keep
current rendering and defaults.

Can go further with goldmark linkify and have this work within markdown
rendering making the link processor unnecessary.

Need to think about how to go about allowing extensions - at present it
seems that these would be hard to do without recompilation.

* linter fixes

Co-authored-by: Lauris BH <[email protected]>

go.mod

@@ -79,11 +79,9 @@ require (
 	github.com/prometheus/procfs v0.0.4 // indirect
 	github.com/quasoft/websspi v1.0.0
 	github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001 // indirect
-	github.com/russross/blackfriday/v2 v2.0.1
 	github.com/satori/go.uuid v1.2.0
 	github.com/sergi/go-diff v1.0.0
 	github.com/shurcooL/httpfs v0.0.0-20190527155220-6a4d4a70508b // indirect
-	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
 	github.com/shurcooL/vfsgen v0.0.0-20181202132449-6a9ea43bcacd
 	github.com/steveyen/gtreap v0.0.0-20150807155958-0abe01ef9be2 // indirect
 	github.com/stretchr/testify v1.4.0
@@ -95,6 +93,7 @@ require (
 	github.com/unknwon/paginater v0.0.0-20151104151617-7748a72e0141
 	github.com/urfave/cli v1.20.0
 	github.com/yohcop/openid-go v0.0.0-20160914080427-2c050d2dae53
+	github.com/yuin/goldmark v1.1.19
 	go.etcd.io/bbolt v1.3.3 // indirect
 	golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876
 	golang.org/x/net v0.0.0-20191101175033-0deb6923b6d9

go.sum

@@ -462,16 +462,12 @@ github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001/go.mod h1:qq
 github.com/rogpeppe/fastuuid v0.0.0-20150106093220-6724a57986af/go.mod h1:XWv6SoW27p1b0cqNHllgS5HIMJraePCO15w5zCzIWYg=
 github.com/russross/blackfriday v1.5.2 h1:HyvC0ARfnZBqnXwABFeSZHpKvJHJJfPz81GNueLj0oo=
 github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR/rfWxYHBV53g=
-github.com/russross/blackfriday/v2 v2.0.1 h1:lPqVAte+HuHNfhJ/0LC98ESWRz8afy9tM/0RK8m9o+Q=
-github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/satori/go.uuid v1.2.0 h1:0uYX9dsZ2yD7q2RtLRtPSdGDWzjeM3TbMJP9utgA0ww=
 github.com/satori/go.uuid v1.2.0/go.mod h1:dA0hQrYB0VpLJoorglMZABFdXlWrHn1NEOzdhQKdks0=
 github.com/sergi/go-diff v1.0.0 h1:Kpca3qRNrduNnOQeazBd0ysaKrUJiIuISHxogkT9RPQ=
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/shurcooL/httpfs v0.0.0-20190527155220-6a4d4a70508b h1:4kg1wyftSKxLtnPAvcRWakIPpokB9w780/KwrNLnfPA=
 github.com/shurcooL/httpfs v0.0.0-20190527155220-6a4d4a70508b/go.mod h1:ZY1cvUeJuFPAdZ/B6v7RHavJWZn2YPVFQ1OSXhCGOkg=
-github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
-github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/shurcooL/vfsgen v0.0.0-20181202132449-6a9ea43bcacd h1:ug7PpSOB5RBPK1Kg6qskGBoP3Vnj/aNYFTznWvlkGo0=
 github.com/shurcooL/vfsgen v0.0.0-20181202132449-6a9ea43bcacd/go.mod h1:TrYk7fJVaAttu97ZZKrO9UbRa8izdowaMIZcxYMbVaw=
 github.com/siddontang/go v0.0.0-20180604090527-bdc77568d726/go.mod h1:3yhqj7WBBfRhbBlzyOC3gUxftwsU0u8gqevxwIHQpMw=
@@ -550,6 +546,8 @@ github.com/xiang90/probing v0.0.0-20190116061207-43a291ad63a2/go.mod h1:UETIi67q
 github.com/xordataexchange/crypt v0.0.3-0.20170626215501-b2862e3d0a77/go.mod h1:aYKd//L2LvnjZzWKhF00oedf4jCCReLcmhLdhm1A27Q=
 github.com/yohcop/openid-go v0.0.0-20160914080427-2c050d2dae53 h1:HsIQ6yAjfjQ3IxPGrTusxp6Qxn92gNVq2x5CbvQvx3w=
 github.com/yohcop/openid-go v0.0.0-20160914080427-2c050d2dae53/go.mod h1:f6elajwZV+xceiaqgRL090YzLEDGSbqr3poGL3ZgXYo=
+github.com/yuin/goldmark v1.1.19 h1:0s2/60x0XsFCXHeFut+F3azDVAAyIMyUfJRbRexiTYs=
+github.com/yuin/goldmark v1.1.19/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/ziutek/mymysql v1.5.4 h1:GB0qdRGsTwQSBVYuVShFBKaXSnSnYYC2d9knnE1LHFs=
 github.com/ziutek/mymysql v1.5.4/go.mod h1:LMSpPZ6DbqWFxNCHW77HeMg9I646SAhApZ/wKdgO/C0=
 go.etcd.io/bbolt v1.3.2/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=