Provide a fix for "dom parse -html ..." for adp tags.
"dom parse -html" has two problems with ADP tags like "<adp:icon ...>":
a) If the tag name contains a colon or underscore, the tag is
treated like plain text, i.e. "<" and ">" are converted into
HTML entities.
b) These tags have to be closed "<adp:icon ...>" is invalid.
Several existomg ADP tags have not closing tag.
Therefore, we resolve the ADP tags before parsing the text by
tdom. There should be some future framework support to do this in
general, but until we have this, resolve this problem here locally.
