order of annotations is now preserved almost

[petravandenbos-utwente]

Since merge 07d831b a contract is printed as follows:

• Select all context annotations: i.e. the annotations occurring in the pre- and post-condition of a contract.
• Print all non-context pre-condition annotations
• Print all context annotations.
• Print all post-condition annotations

Problem:
Annotations are printed in an order such that VerCors cannot verify the contract anymore, e.g. it prints a contract:
requires a == 1;
context Perm(a,1\2);

Solution:
This pull-request works in almost all cases, except for contrived contracts as shown in issue #619

[sonarcloud]

Kudos, SonarCloud Quality Gate passed!

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