`%recipient%` should use reply-to header if present when replying

[RealRaven2000]

When using the %recipient% field in a reply, this is replaced with the %to% variable internally when replying to an email. However it should be set to the final recipient (reply-to) when that field was set in the original email.

[RealRaven2000]

Test versions with a quick fix:

Tb 68: smartTemplate-fx-2.18pre4.zip
Tb 78-91: smartTemplate-fx-3.9.1pre2.zip

to test, as always download the zip file, then drag it (without unpacking) into Thunderbird Add-ons Manager.

[RealRaven2000]

Implemented in 3.10.1 - released on 04/Feb/2022