Updated LaTeX Poster Package

I updated the poster package that I had written for doing large-format conference posters in LaTeX. The updated package uses PGF and TikZ, which is a way of making beautiful figures in LaTeX. I’ve been using pstricks to make figures for a while, and while it works for me, getting it to work with pdflatex is a pain. Luckily, TikZ works in both the PostScript-based workflow as well as the direct-to-pdf workflow. Many thanks are due to Massimo Canonico for his feedback and comments.