Add maxpeers substitution in remaining localization

### For duplicate keys

* [QueueToadlet.panicButton](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L1551) and [QueueToadlet.panicButton](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L1566)
* [SecurityLevels.setPasswordTitle](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L1703) and [SecurityLevels.setPasswordTitle](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L1711)

I also get the sense that unescaped spaces are not allowed in the keys of `.properties` files, (as in [`TOO OLD` and `TOO NEW`](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L228)) but we're using SFS instead, so it's reasonable to conclude that it's nonstandard and just splits each line on `=`.

### Max peers substitutions

Matching [the existing](https://github.com/freenet/fred-staging/blob/8ceecde7a0803836caaf564f59c6064c0fc9417c/src/freenet/l10n/freenet.l10n.en.properties#L1049).

Companion pull request to #174.