Allow custom url schemes

[bleistivt]

I followed the suggestions of #7769

The only difference is, that Garden.Html.CustomUrlSchemes replaces the default config in my implementation. This is because afaik array configs are somewhat deprecated and because of HtmLawed's special scheme syntax which doesn't really map to an array. String concatenation would be another option.

[charrondev]

I don't think we'd want to concat the default ones as that prevent people from removing allowed schemes from their config.

There are 2 changes I would request though, mostly because I'd prefer to be able to re-use the same config value in Rich Editor in the future.

• Make the config value Garden.Html.AllowedUrlSchemes.
• Have the config value be an array of strings (was there somewhere you saw referenced disallowing arrays in the config? I think it's only serialized arrays that are being discontinued, but maybe @tburry knows better). I know for sure use an array for Garden.Uploads.AllowedFileExtensions and I don't think that's going anywhere anytime soon.
• Join that array into a string to insert into this rule.

[bleistivt]

Based on this comment, but it is quite old:
#4043 (comment)

The problem is that the HtmLawed config defines multiple groups:

classid: clsid;
href: aim, feed, file, ftp, gopher, http, https, irc, mailto, news, nntp, rapidminer, sftp, ssh, telnet;
style: nil;
*: file, http, https'

http://www.bioinformatics.org/phplabware/internal_utilities/htmLawed/htmLawed_README.htm#s3.4.3

Do you only want the href group to become Garden.Html.AllowedUrlSchemes?

[charrondev]

Do you only want the href group to become Garden.Html.AllowedUrlSchemes?

That's what I was thinking. Do you have any need of specifying the other ones? I feel like as a config setting it would be more useful if it didn't have to be based around Htmlawed's specific syntax.

Rich editor for example, would like to use a shared config setting, and that doesn't use Htmlawed at all.