Fix issue with "./" in require path on Windows
Fix issue with "./" in require path on Windows

The check for relpath starting with "." or "/" does not work on Windows, as
paths can start with a drive letter (e.g., "C:\"). Now path.dirname() is used
to determine the case where "./" is needed.

Closes #59.

apihlaja/insert-module-globals,substack/insert-module-globals,apihlaja/insert-module-globals,substack/insert-module-globals