Reply as linked topic should default to same category

[cpradio]

Slightly related:

Disallowing "uncategorized" entries still offers uncategorized as default category

Okay, so a PR that put Select a Category when Create Topic from the Latest page and defaulted to the current Category when using Reply as New Topic would be accepted? Just making sure I understand what you deem to be appropriate, so I can throw it on a “look into, to see if I’m comfortable making this change” list.