Use agnostic path separator in data import

[ratollama]

I'm currently working on linux, and Schema Zen appears to run well on mono (great!)
The only glitch I have is that the data import does not work (it does not found the data folder) if I don't run export MONO_IOMAP=all before run schemazen.exe.
I thing this can be because in the ImportData method there is a windows path backslash separator.