Migrate overlapping intent attributes in closed and open list

[physikerwelt]

According to my import script, there are some entries that exists in both, open and closed list. We should merge the contents (as the open list is much better) and remove one of the entries.

Examples:

• floor closed open
• fractional-part
• golden-ratio
• identity-matrix

[physikerwelt]

As an alternative, we could abandon the core list and make an attribute that some of the concepts are more important than others.