Move to picoc instead of lua

[jakibaki]

Picoc is a c-interpreter which imo makes much sense than lua since we have native pointers and proper types.

With #11 this will enable users to just access process-memory from a pointer inside the c-script so they can for example define structs and directly point that struct to game-memory.

Since unlike lua this doesn't have speed as its target performance is going to suffer a bit though the ability to access native pointers removes the need to copy memory all the time so it might actually be faster.

[jakibaki]

My current experiments with picoc on the switch are at https://github.com/jakibaki/testpicoc

[jakibaki]

Picoc appearently has problems with arithmetic of u64-numbers. I'll need to investigate and fix that.

Fixed (at least fixed enough for my purposes).