Adding Essentia Synth

This is the block I've been working on as a way to familiarize myself with the codebase, hopefully can help fix things in the future.  Getting this into mainline makes my life easier as I don't have to maintain two separate repos just to work on TT.

The essentia synth is an adaptation of the essentia funnel concept, except instead of moving essentia around it allows for merging two aspects into their compound result.  So a jar of Aer + jar of Ignis = jar of Lux.  Like the essentia funnel it requires placement over a hopper though I'm looking to change that in the future and make it a stand-alone block.  Right now it more or less works as advertised.  Recipe and book text are of course up for grabs.
I've had long discussions about balance with friends and I think this can be integrated without gamebreaking problems.  The default behavior is to produce at a (2:1) ratio so a full jar of each component only produces a single jar of the result.  This restriction is removed when ichor is placed in the funnel.  I don't *think* this kind of mechanic actually breaks anything though plenty of people seem to think it'd be the end of the world.  I believe there's a place in TT for this functionality though exactly where and how expensive isn't clear.  

In a related note this pull also alters TTResearchItem slightly so hidden pages can be created.  Dead-simple example is used in the block to hide the second page until ichor is unlocked.  I don't believe creating hidden pages is possible without this change.

This is very much an on-going project and not ready for release, which is why it is configured to not show up under the creative tab and the research is disabled via comment.  I thought I'd throw it open to comments before sinking too much time in a block that moves the project in a direction you guys don't want it to go.