restructured structure folder and added stuff

[J-T-de]

too lazy to split the changes in separate PRs, but I think most of them are reasonable. Check out my fork to see the result.

some stuff is definitely needs to be discussed moved files around:

structure is now

• sourcehold-maps/structure/kaitai/
• sourcehold-maps/structure/cheatengine/
• sourcehold-maps/structure/map_structure.h

created construct definition (especially check out construct_map.py, there is lots of stuff documented which needs to be incorporated to the wiki)

• sourcehold-maps/structure/construct

added README.md for all folders I touched with brief descriptions

To discuss:

• how to document *.CSX data properly (I created a example Unit.md, but I am myself not sure if this is good)
• should we keep map_structure.h, it is really well documented, but so is the wiki. I also think who can understand map_structure.h can understand kaitai_map.ksy. Not sure on this one

TODO:

• finish CONTRIBUTING.md
• finish sourcehold-maps/structure/cheatengine/README.md
• refactor sourcehold-maps/cheatengine, basically tear apart the scripts and put them in single lua files as I did here
• update the wiki with the findings

[J-T-de]

This is all I touch for now. I think the big todos are done. Can be merged. Please notice: I touched the main README.md, restructured it a little bit and added the discord button

Still to do

• split /cheatengine
• wiki updates