Add support for project dependencies

[https://me.yahoo.com/a/teho7iigkp7drpi2ox0ipk6s_vpgdtxhfwzd9po-#29fb6]

A need for expression of dependency information in DOAP has been expressed a couple of times on the mailing list [eg. 1,2]. As a start, the attached patch adds dependency support to the DOAP ontology definition. A property 'dependency' is added in the way that's (AFAICS) most advocated on-list. This means that a doap:Project can have a doap:dependency on another doap:Project.

In XML notation (from [1]):

<Project...

<dependency>

<Project rdf:about="http://python.org">

<name>Python</name>

</Project>

</dependency>

</Project>

[1] http://lists.usefulinc.com/pipermail/doap-interest/2009-September/000380.html [2] http://lists.usefulinc.com/pipermail/doap-interest/2009-August/000378.html

[https://me.yahoo.com/a/teho7iigkp7drpi2ox0ipk6s_vpgdtxhfwzd9po-#29fb6]

Patch to add dependency property to DOAP ontology