Or, a very very tedious way to simulate embassies in 1.2:

Step 1: Offer an AI you want to butter up Star Charts (or 1 energy or 1 mineral) for nothing. They will always accept, and so you'll get a small opinion bonus with them.
Step 2: Do it again. They will still accept, and the deal will be exactly 1, so you will get 2 opinion with them.
Step 3: Repeat up to 50 times for lots of opinion bonuses.

Since attitude is tied to opinion (multiple times an empire has become Friendly to me from Cordial at exactly 100 opinion), it's usually pretty easy to push empires over the edge of an alliance with this trick.

(Paradox: Please remove the "Gift: 1" modifier on trades. I am pretty sure that the empire I just gave Star Charts to doesn't actually give a shit about my Star Charts any more.)