Open dimacs files broken

[meinicke]

Prerequisitives

• Eclipse Version: 2018-12
• FeatureIDE-Version: 3.5
• Operating system: WIN 10
• Java runtime used to run eclipse: 1.8
• FeatureIDE Composer: Feature Modeling
• Git branch/Commit-ID: N/A
• Java compiler used to build the FeatureIDE plugin: N/A

Issue description

Opening a dimacs file with the Feature Model Editor has two bugs (I used a non-FeatureIDE project):
(1) all the features are shown in the top left corner
(2) constraints are duplicated everytime the editor is reopened

The dimacs file I used:

c 1 base
c 2 KEYS
c 3 ENCRYPT
c 4 AUTORESPONDER
c 5 ADDRESSBOOK
c 6 SIGN
c 7 FORWARD
c 8 VERIFY
c 9 DECRYPT
p cnf 9 6
-3 9 0
-9 3 0
-3 2 0
-6 8 0
-8 6 0
-6 2 0