Another aid with library is Dark Age's rewarding and enabling of trashing. First, count the trashers - the base set has chapel (godly), moneylender (lousy), and remodel (highly situational); Dark ages has Altar, Count, Counterfeit, Forager, Hermit, Junk Dealer, Mercenary, Rats/Action junkers (e.g. Rats/Grave robber), and Dame Anna. Dark Ages is much better at getting rid of the biggest killers of Lib decks - curses, coppers, and estates.
So, first, you can just trash stuff more often with DA in the mix. Second, Dark Ages rewards you very heavily for the trashing that you so often want to do with a Lib deck. Yeah Oge, Rats, and Cultist are a wash, but things like Market square, Squire, and even Feodum can pack nice payouts for what Lib already wants you to do.
There are also a number of very powerful cards that like Libs mechanisms:
1. Count - So it can be a power trasher (though often not until the second reshuffle), it gives 3 coin for 1 action and -1 or -2 cards ... card loss directly made up by Lib's drawing.
2. Storeroom - so let's see it converts cards in hand to cash - so Lib/village/Strm is at least +4 coin, but it also allows you to sift so you can hunt for key cards not currently in your 7 card hand (e.g. have 2 actions, play Strm, pitch 6 cards, look for a village/Lib in the next 6). As an added benefit, it comes with a +buy so you can actually, you know use the 16 coin you generated off 3 Strm and 3 Lib).
3. Wandering minstrel. It is a village, great, Lib needs those. It filters out the crap Lib is forced to draw like coppers and estates, even better. It also let's you manage your to deck to say, place a Lib on top to be drawn so you can draw it with a cantrip and keep the turn going.
4. Squire - it's a village, it's a +buy, it's a cheap disappearing +coin card. Lib really likes all of those. Seven coin with 2 buys? Lib/Squire. It may not be as good as hamlet, but it is extremely good with Lib.
5. Poor house - the most cost effective spammable action-cash in the game. If you are trashing down for a Lib deck, this beats most other options silly.
6. Band of Misfits - yeah 5 coin cards should have stronger effects than 2-4, but there is something extremely strong about being able to play BoM as a village, +coin, trashing, or even +cards as needed. Lib decks are prime candidates where you'd really rather buy the 3 coin card (like Chancellor) over the 5 card coin (like your second Ghost Ship) so added flexibility is big.
Shelters also favor traditional lib decks. As noted, Necro is extremely good with Lib. Hovel is also decent - if you have a money trasher (e.g. Loan), it is one fewer dead card to gum up a library engine. Another important shot is that this means a lean Lib deck isn't down 3 VP verses a BM deck or similar. Shelter concerns can tilt a close call between a Lib engine and a BM deck to the Lib.
Note, for most of this, Watchtower is even more favored than Lib. Wt's trash on gain and top deck on gain are just great with Dark Ages.