Redmine

Textile and Markdown formatter in Redmine adds "external" class to a element when rendering links to an external site. Here is an exmaple:

Textile:

"Redmine":http://www.redmine.org/

Rendered HTML:

<a class="external" href="http://www.redmine.org/">

Although those formatters adds "external" class like as above, links on custom field values, which can be configured in "Link values to URL" of custom fields, don't have "external" class. I am in trouble with this behavior because I use UI theme that provides JavaScript code which opens external link in a new browser window (please see https://github.com/farend/redmine_theme_farend_basic/blob/master/javascripts/theme.js#L3).

I think that links on custom field should have "external" class for consistency and convenience. Attaching a patch to fix this.