Make import path validation case-sensitive and independent from OS

[frademacher]

The validation of import paths should consider case-sensitivity and be independent from the used OS.

Suppose the following filesystem structure:

- smodel.services
- technology
    |- tmodel.technology

Currently, it is possible under Apple or Windows to write the following in the service model smodel.services:

// Import from folder "Technology" whose name in the filesystem is actually "technology"
import technology from "Technology/tmodel.technology" as tech
...

However, the above model will be erroneous on Linux systems, whose filesystems are usually case-sensitive. Thus, import path validation should become case-sensitive and OS-independent to work on all major OSes.