Adding MathJax3.

Current port www/mathjax is for now legacy version, v2. Current version
of MathJax is v3. v2 is still supported and gets patch releases, but v3
is intended for new deployments.

Upgrading v2 to v3 is not in-place upgrade, url of the script changes,
which also requires change config of web server which hosts it.
Therefore I think it is better to introduce new version as mathjax3.

PR:		248796
Submitted by:	Marko Cupać (maintainer)

www/Makefile

@@ -328,6 +328,7 @@
     SUBDIR += madsonic
     SUBDIR += man2web
     SUBDIR += mathjax
+    SUBDIR += mathjax3
     SUBDIR += mathopd
     SUBDIR += matomo
     SUBDIR += mattermost-server

www/mathjax3/Makefile

@@ -0,0 +1,31 @@
+# $FreeBSD$
+
+PORTNAME=	MathJax3
+DISTVERSION=	3.1.2
+CATEGORIES=	www math
+
+MAINTAINER=	marko.cupac@mimar.rs
+COMMENT=	Cross-browser JavaScript display engine for mathematics
+
+LICENSE=	APACHE20
+LICENSE_FILE=	${WRKSRC}/LICENSE
+
+USE_GITHUB=	yes
+GH_ACCOUNT=	mathjax
+GH_PROJECT=	MathJax
+GH_TAGNAME=	c829235
+
+NO_BUILD=	yes
+NO_ARCH=	yes
+
+# Changing permissions of 30k files with find -exec (COPYTREE) is way
+# too slow.
+do-install:
+	${MKDIR} ${STAGEDIR}${WWWDIR}
+	(cd ${WRKSRC} && \
+		${FIND} -d . | ${CPIO} -dumpl ${STAGEDIR}${WWWDIR} >/dev/null 2>&1)
+	${FIND} -d ${STAGEDIR}${WWWDIR} -type d -print0 | ${XARGS} -0 ${CHMOD} 755
+	${FIND} -d ${STAGEDIR}${WWWDIR} -type f -print0 | ${XARGS} -0 ${CHMOD} ${SHAREMODE}
+	@(cd ${STAGEDIR}${PREFIX}; ${FIND} -s ${WWWDIR_REL} -not -type d) >> ${TMPPLIST}
+
+.include <bsd.port.mk>

www/mathjax3/distinfo

@@ -0,0 +1,3 @@
+TIMESTAMP = 1606216920
+SHA256 (mathjax-MathJax-3.1.2-c829235_GH0.tar.gz) = dee27f0fbb4b260d7e64b74911b9edcfa7c1ddd0995cc6901e772683283c6f74
+SIZE (mathjax-MathJax-3.1.2-c829235_GH0.tar.gz) = 4743286

www/mathjax3/pkg-descr

@@ -0,0 +1,4 @@
+MathJax is an open source JavaScript display engine for mathematics
+that works in all modern browsers.
+
+WWW: http://www.mathjax.org/