Intro prompt to self-determiination

[GabrieleBattaglia]

I put my ideas here for your convenience.

When program starts, put a little intro prompt of itself, especially

• including the version number
• Data of last release
• URL of the project
• author's detail
• reminder to call help for menu commands

[tage64]

f6126f5 and 1bef2d3 implements most of these suggestions.