version scheme and ABI/API compatibility

[karolherbst]

I want to stick to this: http://semver.org/

We should not "force" these rules, but try to keep them in mind. That means:

• 1.0.0 => 1.0.x must not break ABI and API
• 1.0.x => 1.y must not break ABI and must be API backward compatible
• 1 => z should not break ABI (if we can avoid it, we avoid it)

Other than this, should be common sense and respect Semantic Versioning.

Please keep this nice KDE page in mind: http://techbase.kde.org/Policies/Binary_Compatibility_Issues_With_C++

Some Policies developers should keep in mind:

• you should add a comment for later API changes, e.g. functions/methods should be merged, with // API: ...

[Cheeseness]

Sounds good to me.

[karolherbst]

added to wiki: version scheme and ABI API compatibility