Add a program to generate a Haskell source file containing the primitives environment.
It will be used to generate the primitives environment in the compiler.
Remove some dead code.
Add a variant for strings in value. Add basic type convertsion primitives.
Strings are now garbage-collected
Remove the symbol table from the VM, and replace it with a generic string interner in the GC.
Use LeoTestard/rust-gmp as remote for the rust-gmp submodule. Update submodule.
Fix build for Rust master.