Introduce an easy identifier that changes every time a Solidity source changes

[pirapira]

Since #1023 was merged, it has become harder to recognize the version from a Solidity source.

Perhaps each file can contain an ever-increasing integer. My biggest wonder is how not to forget incrementing the number.

[ulope]

Perhaps each file can contain an ever-increasing integer. My biggest wonder is how not to forget incrementing the number.

Automation :)

[pirapira]

I vaguely remember Emacs had some tricks to save the "updated-at" field in a file.