Database connectivity section

[chuchana]

A "Database connectivity" section should be added using
the CLSQL library (by the UFFI author) before any
implementation specific methods.

http://clsql.med-info.com/

[Frederic Brunel @ http://sourceforge.net/p/cl-cookbook/feature-requests/3/]

[pnathan]

Is CLSQL still viable? I can't recall anymore.

[PuercoPop]

It is, it @AccelerationNet uses it and has some helper libraries. But idk it is the most popular choice nor that it should be the only one.

[eudoxia0]

We should use cl-dbi and sxql

[vindarel]

I'm about to write about Mito and SxQL, telling you so than you can ping me if I'm long in doing so :)

[vindarel]

WIP: https://vindarel.github.io/cl-cookbook/databases.html (https://github.com/LispCookbook/cl-cookbook/compare/master...vindarel:database?expand=1)

[vindarel]

merged: #175