Roundcube remote resources fix and tidy (#343)

Due to how mailcow is configured security wise, some people may get this issue https://github.com/roundcube/roundcubemail/issues/8170 depending on their browser. When you go to press `Allow` to show remote content within an email, it'll redirect you to the root of the website, in this case mailcow login. This fix should be included in the Roundcube 1.6 release, until we hit this release we just need to apply the fix manually for each install/upgrade.

docs/third_party-roundcube.md

@@ -5,11 +5,15 @@ Download Roundcube 1.5.x to the web htdocs directory and extract it (here `rc/`)
 # Check for a newer release!
 cd data/web
 wget -O - https://github.com/roundcube/roundcubemail/releases/download/1.5.2/roundcubemail-1.5.2-complete.tar.gz | tar xfvz -
+
 # Change folder name
 mv roundcubemail-1.5.2 rc
 
 # Change permissions
 chown -R root: rc/
+
+# Fix Allow remote resources (https://github.com/roundcube/roundcubemail/issues/8170) should not be required in 1.6
+sed -i "s/\$prefix = '\.\/';/\$prefix = preg_replace\('\/\[\?\&]\.\*\$\/', '', \$_SERVER\['REQUEST_URI'] \?\? ''\) \?: '\.\/';/g" rc/program/include/rcmail.php
 ```
 
 If you need spell check features, create a file `data/hooks/phpfpm/aspell.sh` with the following content, then `chmod +x data/hooks/phpfpm/aspell.sh`. This installs a local spell check engine. Note, most modern web browsers have built in spell check, so you may not want/need this.
@@ -174,7 +178,6 @@ Upgrading Roundcube is rather simple, go to the [Github releases](https://github
 docker exec -it mailcowdockerized_php-fpm-mailcow_1 bash
 
 # Install required upgrade dependency, then upgrade Roundcube to wanted release
-
 apk add rsync
 cd /tmp
 wget -O - https://github.com/roundcube/roundcubemail/releases/download/1.5.2/roundcubemail-1.5.2-complete.tar.gz | tar xfvz -
@@ -183,9 +186,10 @@ bin/installto.sh /web/rc
 
 # Type 'Y' and press enter to upgrade your install of Roundcube
 
-
 # Remove leftover files
-
 cd /tmp
 rm -rf roundcube*
+
+# Fix Allow remote resources (https://github.com/roundcube/roundcubemail/issues/8170) should not be required in 1.6
+sed -i "s/\$prefix = '\.\/';/\$prefix = preg_replace\('\/\[\?\&]\.\*\$\/', '', \$_SERVER\['REQUEST_URI'] \?\? ''\) \?: '\.\/';/g" /web/rc/program/include/rcmail.php
 ```