Cleanup assets and jar META-INF

[metc]

I made this issue regarding the commit ebba414 from @lambdaShade. The asset folder included in the mod realase jar maybe need some cleanup. IMO, it looks ok now.

I think the size of the release jar file is not a really big issue... The assets/eln folder contains 619 files (~ 4Mo). Currently, every models are included in the release file, event if they are not used in the game.

I check the asset folder content. here are some open questions:

1. Is the model\_Common needed ?
2. Is the file https://github.com/Dolu1990/ElectricalAge/blob/1.7.10-MNA/src/main/resources/assets/eln/model/ElectricalSensor/myTex%20-%20Copie.png need ?
3. Some files are mixed between relay800 and RelayBig
4. Is the file replicator/replicator.tcn used ?
5. Which Blender files are required for the stoneCache model ?
6. Is the file TemperatureSensor/myTex - Copie.png needed ?
7. Is the file VoltageSensor/myTex - Copie.png needed ?
8. Files export_block.png, export_cable.png and export_sixNodeWall.png should not be included in the release jar, correct ?
   1. Are the files items/miaou.png and items/tiningot.png needed ?

As proposed by @cm0x4D, I will setup a new filter for the asset folder. Only .png, obj, mtl, txt files must be included for the models, ogg for the sounds, lang for languages and png for all textures and sprites.

[metc]

The manifest file of the release Jar must also be updated in order to publish the mode to Maven Central.

[cm0x4D]

We should first define a folder layout and then rearrange the files to that scheme and after that we can create a useful inclusion filter. The gradle script should not just copy folders into the jar, we could define different rules for different kinds of files and for example move all models into the same target folder.

Another thing that bothers me is that we have to list each model to load in Eln.java. If we have an intelligent data scheme, we could just load all models from a folder at startup. Would be much easier IMHO.

[lambdaShade]

I think we have to discuss of this point all together in a meeting...