This is mostly done, since the html symbols are now in a new package called "Text".
But maybe we should move 'document' there, and rename it to "Documentation".

change to priority 1

get rid of unused two letter names!

horrible ones:

    F4 SY 

bad ones:

    BR DD DL DT EM HR LI
    TD TR

questionable ones:

    hh

good ones: 

    CC pi QQ RR dd OO
    TO TT UL

Also, hide all the html symbols in a separate package called HTML (rename HTML
first) and have getPackage() and SimpleDoc open it with needsPackage()
automatically.

The Symbol SPACE Thing error message could look in the loaded packages to see
if needsPackage is needed, and suggest it
