Notes:

1) get_all_text

check out loncom/homework/structuretags.pm start_block for an example
use. It works like HTML::TokeParser->get_text().

Additionaly note the existance of a depth counter similar to the one
in Gerd's original lonproblem.pm

2) depthcounter
$Apache::lonxml::curdepth will be a string like:
2_3_1

(tag 1 in the 3 second level tag in the 2 toplevel tag)

It gets set by callsub and is available for use in the Perl tag
implementations.