Fixed, changed addresses in README. Made README look better on Github.

Fixed, changed addresses in README. Made README look better on Github.

Why not add README.md? Not enough reasons to warrant info duplication:
Markdown is not particularly helpful for rendering a trivial list of
references, and Github already renders HTTP links appropriately.

Why not move README to README.md? Many tools and console humans still
look for README rather than README.md.

Why not use Markdown in README? Github does not render such markup.

TODO: Consider removing detailed distribution terms at the bottom
because "everybody" knows what GPLv2 basically means, and we already
tell the reader where to find the exact licensing terms.