stories with custom icons containing spaces are not imported

[hofstef]

Describe the bug
In old Egon versions (presumably <= 1.3.0) it was possible to upload custom icons with spaces in its name, e.g. "my icon.svg". Domain Stories containing such custom icons are not imported.

To Reproduce
Steps to reproduce the behavior:

1. Import a domain story that uses a custom icon like described above, e.g. openingstory-00-symbols.dst
2. See error:

unhandled error in event listener TypeError: icon is null
    isCustomIcon util.js:54
    getIconSvg domainStoryRenderer.js:384

Expected behavior
On import (domain story and iconset), whitepsaces in custom icon names are replaced with "-", which is consistent with the current behavior for uploading custom icons with whitespaces.

Desktop (please complete the following information):

• Modeler Version: v2.0.0

[hofstef]

fixed with v2.0.1