Image links based on RFC2397 not supported

[Dirk Stöcker]

Directly included images in this RFC format ​http://tools.ietf.org/html/rfc2397 aren't supported. They don't work in [[Image()]] macro nor in #!html processor.

data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACgAAAAoAQMAAAC2MCouAAAAA1BMVEXLQ0MOAUiXAAAAC0lEQVQIHWMYYQAAAPAAASEIRrcAAAAASUVORK5CYII=

See also #8168 which comes up again, as there is a comma in the string which can't be encoded as %2c, otherwise fix would be easy.

Fix for "data:" is easy, simply handle it like http:, but the comma is a problem again. Proper argument splitting is required.

macros.

@@ -581 +581 @@
         parts = filespec.split(':')
         url = raw_url = desc = None
         attachment = None
-        if (parts and parts[0] in ('http', 'https', 'ftp')): # absolute
+        if (parts and parts[0] in ('http', 'https', 'ftp', 'data')): # absolute
+            if parts[0] == "data":
+              filespec = filespec.replace("%2C", ",")
             raw_url = url = filespec
             desc = url.rsplit('?')[0]
         elif filespec.startswith('//'):       # server-relative

Simple patch with a workaround for the comma issue.