Avoid double including a cause

If a requirement is the cause of multiple
incompatibilities then don't include it twice
in the cause list.

Change-Id: Ic6372f71c70fd06a8d28678b37f3dbf50c8f75c4
Fix scoring conflict

When a requirement set contains >x and >=x and when
x is the same version we should mark this as a conflict
since both can not be valid. The same goes with the <x
and <=x version.

Change-Id: I2562295d22a589a67dba2abc10ea376709a4c09c
Merge "Avoid double including a cause"