GitLab

If you want git blame to ignore formatting revisions run:
git config blame.ignoreRevsFile .git-blame-ignore-revs

If you want git blame to ignore formatting revisions run:
git config blame.ignoreRevsFile .git-blame-ignore-revs

Adds `override` if it is missing,
removes `virtual` if it's unneeded,
also converts:
`virtual foo();`
to:
`foo() override`
in descendant classes.

(Can be meaningful if memory is dynamically allocated.)

Also add a context object to callback registration.