Overarching Issue for series of TLM/adjoint work

[tom-j-h]

There was a large amount of work done during the previous code freeze which has been used for JADA benchmarking. We are now aiming to get this onto trunk.

For the parts I'm doing, it's much simpler to do them as a series of dependent PRs. This is an overarching Issue to note down the dependency order.

Issues:
(#40) <- #84 <- #124 <- #85 <- #125 <- #126 <- #129

PRs:
(#71) <- #123 <- #132 <- #156 <- #161 <- #163 <- #182