Rename hello world into hello bayhac
Update slides
Merge commit 'f8292b304d3a25de708a26d9f75d21907e0d882d'

* commit 'f8292b304d3a25de708a26d9f75d21907e0d882d':
  Rename hello world into hello bayhac

Conflicts:
	contrib/hello-bayhac-ffi.hs
	contrib/hello-bayhac-ffi.html
	contrib/hello-bayhac.html
	slides/main.md