lang: Fix tail calls not dispatching on object_none

lang: Check against None, not truthiness

lang: Clarify denominator is always 1 in bytecode

lang: Remove useless abort

lang: Use an object_list for use_modules

lang: Convert vm to use an object_list

lang: Add an object_list structure

lang: Declare opaque structs for better type safety

lang: Mark tail_obj as not a pointer

lang: Be explicit about ModuleInfo's constness

lang: Don't imply vm_tailcall uses a queue

lang: Clean up one-line if statements

lang: Clarify usage of traverse_module_uses

lang: Use calloc for vm_create

lang: Rename module args to use_modules

lang: Pass dependencies to modules

lang: Switch to for loops for string iteration

lang: Create a module and find its dependencies in a new function

lang: Fix const uses for ModuleInfo

lang: Create modules and dependencies on request

lang: Don't double traverse visited modules

lang: Fix another off-by-one error

lang: Remove unused include

lang: Rename module_stack top to next

lang: Fix off-by-one error stack setting

lang: Support multiple traverses

lang: Moved visited stack to module_find

lang: Switch to depth first search for modules

lang: Add module loading dependency walker

lang: Print all done when main is finished