Revise versioning

[sgtp]

The current mechanism of version management assumes the possibility of different versioning branches, and it has a few limitations:

• It relies of version number to be of the form "stringNumber"
• When multiple branches are present, the system is largely inconsistent: the most recent branch returns a random one

The mechanism should be refactored to accommodate more generic version identifications (e.g.: numbers only?), and to cope with multiple version branches. For instance by some diff&merge command (see #9 ).

[sgtp]

The objective is to have a simple version implementation (single number), rather than more complex schemes.

[sgtp]

Simple version implementation is in place. Versions like "v0" results now in a configuration error (they could easily be allowed if needed).