n-body links

Added links to n-body solution information on algorithms and formulae part of astro and s/w links.

+Linx II

A few more astronomical links added: CDS archive database (CDSARC) at University in Strasbourg, a spectral types link to ESO, and a link to PostgreSQL.

+Linx I

Added some Astronomical links for:

1. general public inspiration,
2. mayhap collaborators,
3. "competitors" (this is OpenSource, competitors are really passive collaborators), "competition" is welcome, and "competitors" are welcome!
4. astronomy surfers

Feel free to propose additions!