Fixes #921

# Description
This branch contains all fixes that I needed to work with the
UZF-package. The branch contains:

1- Changes to UZF- package methods
2- Changes to the open_cbc methods to deal with cbc-files of advanced
packages
3- Changes to the UZF-tests + all tests that deal with budget output

There are some breaking changes in budget output names:
1- The new names support now support output of multiple equal boundary
packages, since the package name is used.
2- The budget arrays now contain nans if a package is not active, since
zero is a valid budget output.

# Checklist
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- [x] Links to correct issue
- [x] Update changelog, if changes affect users
- [x] PR title starts with ``Issue #nr``, e.g. ``Issue #737``
- [x] Unit tests were added
- [ ] **If feature added**: Added/extended example