fix url-generated images (& converted to &amp;)

There was (not only in [img] and !\[\](imagelink) ) a problem with urlencoded & (ampersand) (& -> &amp;): this behaviour breaks all the "url-generated" images.
an example is http://alfa.nwa/gimmeimage?type=cat&w=500&h=140 : now the link does _not_ contain &amp; instead of &.
Previous commit is related to (auto)urls and automated linking too!

for the automated linking, I had to "replace" &amp with &, as the conversion is done previously.