plugin versions

[bvdberg]

When plugins and the c2c binary are based on different AST versions, crashes will happen.

I just pushed a branch plugins-versions that uses the git version to check if both c2c and the plugin(s) originated from the same build. This might be a bit too restrictive, but it does solve the issue.

It even lets the git_version plugins depend on itself :)

Another idea might be to have an AST version (just a number). Whenever the AST memory layout is changed, this number should be updated. This will be less restrictive, but people are very prone to forgetting this number...