.topdeps files that don't have a trailing newline will ignore the last dependency

This isn't technically a bug, but it can be annoying / confusing - currently, .topdeps files are REQUIRED to have a trailing newline, and if not, the last dependency will be silently ignored.

Removing this requirement will remove some potential confusion / bugs, if hand-editing .topdeps files

Fixed in https://github.com/greenrd/topgit/pull/62