Migrate Google Summer of Code historical information from Wiki

[blast007]

The wiki contains some information about our previous involvement in the Google Summer of Code program. This information could be created as sub-pages of the Project History section and linked from the relevant milestones.

https://wiki.bzflag.org/Google_Summer_of_Code
https://wiki.bzflag.org/Google_Summer_of_Code/2007
https://wiki.bzflag.org/Google_Summer_of_Code/2008
https://wiki.bzflag.org/Google_Summer_of_Code/2009

[TheGiraffe3]

I'm looking around, but can't seem to figure out where I would create the new files/add the information. Could I get some help on that, please?

I've created three files, but I don't know how to link to them from the other files. The PR with everything so far is #51.