Add entity type to HTML reports.

[Linas Vepstas]

Log Message:
-----------
Add entity type to HTML reports.  Remove xaccGUIDType usage.
The xaccGUID usage was totally broken, clicking on report links
probably used to core dump; broken report links should now be fixed.

(This change probably conflicts with a jsled change to gnome2;
jsled, since this is the "more correct" long-term change as discussed, 
please reert teh other changes.)

Modified Files:
--------------
    gnucash/src/report/report-system:
        html-utilities.scm
    gnucash/src/gnome:
        top-level.c