Big upgrade to NLS

[arjendevos]

Again, not sure whether you were also working on it but I needed some better language server support.

[weiwenhao]

I didn't make any major changes; I simply synchronized the relevant syntax to nls when there were syntax changes in the compiler. The related refactorings were already merged into master earlier. You can improve nls as needed; my focus is more on the compiler.

In addition, you may be able to design a testing mechanism for nls so that you can get better feedback when nls is refactored.

[arjendevos]

@weiwenhao did a complete rewrite of the nls. The nls is now basically completed with only a few things left but those are future things.

[weiwenhao]

The current branch and master branch have conflicts. This is due to semantic.rs being split into multiple smaller files. You need to update your master branch, merge or rebase master into the current branch, and resolve the conflicts before merging.