Missing static background map

[forman]

Expected behavior

When Cate Desktop is in offline-mode (File / Preferences / Force offline mode) a static background map should be displayed (low-res Natural Earth 2.0).

This only occurs in the installed version. When run from sources everything works as expected.

Actual behavior

The static map isn't displayed. Instead nothing is shown (see #448).
The reason for this is that the static resources of the map are not packaged in the Cate's setup.py.

Steps to reproduce the problem

In the installed Cate Desktop:

1. Check File / Preferences / Force offline mode
2. Restart Cate Desktop

Specifications

Cate / Cate Desktop 1.0.0.dev1

[mzuehlke]

Fixed by 3144254