add a .clang-format file and format the repo

[AuroraPerego]

BEGINRELEASENOTES

• add a .clang-format file and format the repo

ENDRELEASENOTES

[tmadlener]

Thanks a lot for this. Since we have a common .clang-format to ensure consistent formatting for all Key4hep repositories, I would prefer if we used that also here, unless there are compelling reasons not to do that.

[AuroraPerego]

Thanks a lot for this. Since we have a common .clang-format to ensure consistent formatting for all Key4hep repositories, I would prefer if we used that also here, unless there are compelling reasons not to do that.

Oh, I did not know that :)
I just used one I was already using in another place, I can move to this one.

[jmcarcell]

I updated the common .clang-format, reformatted the repository and added the commit to .git-blame-ignore-revs. Can you try to exctract the changes #67 that are not formatting and rebase? I would not try to solve the conflicts, just simply try to apply the changes again (I think it's easier?).

[AuroraPerego]

I updated the common .clang-format, reformatted the repository and added the commit to .git-blame-ignore-revs. Can you try to exctract the changes #67 that are not formatting and rebase? I would not try to solve the conflicts, just simply try to apply the changes again (I think it's easier?).

done!