#3 Add administrative informations on GANTT

[Guilhem BONNEFILLE]

It would be usefull to have some 'administrative'
informations on GANTT. It's to say:
- generation date in the header (ie: "Generated in
2003/01/09"),
- advertising in the foot (ie: "Made with opensched 0.4"),
- the list of files used could also appear in the foot.

A project name could be also a good addition in the header.

This would be usefull when the gantt is used alone.