taxonomy checkboxes other

Hey guys,

I have been trying to get an image gallery setup at work and I noticed a few things that I think should be added to taxonomy.

First, a simply modification to _taxonomy_term_select() allows for checkboxes instead of the dreaded multiselect box, which requires the CTRL key in order to pick out certain terms. Less knowledgeable users cannot be expected to know of this CTRL function, and thus I believe that checkboxes would be much more desireable.