Fix maktaba#path#Split on Windows to also split on '/' characters

Changes `maktaba#path#Split` on platforms that use backslash (Windows and OS/2) to always use both forward slash and backslash as separators.

Hopefully fixes #71.
@glts Can you confirm? It passes all tests and seemed to work as intended when I hard-coded it to use the backslash version on my system.

BTW, I'm not sure `maktaba#path#RootComponent` is correct, either.