define-library and import (R7RS)

This feature should be added to version 1.0

This is early implementation of module macro before I've knew about `define-library` or even before I've started working on R7RS spec, it can be refactored into R7RS library.

```scheme
;; -----------------------------------------------------------------------------
(define-macro (module name . body)
"(module module-name . body)

Macro for defining modules inside you can use define to create functions.
And use export name to add that name to defined environment."
(let ((parent (. (current-environment) '__parent__))
(module-name (gensym)))
`(let ((,module-name (new-module ,(symbol->string name))))
(define-macro (export name) `(--> ,,module-name (set ',name ,name)))
,@body
(--> ,parent (set ',name ,module-name)))))

;; -----------------------------------------------------------------------------
(define-macro (import name module)
"(input function-name module)

Macro for importing function from module"
`(define ,name (--> ,module (get ',name))))

;; -----------------------------------------------------------------------------
(define-class Module Object
(constructor
(lambda (self name env)
(set-obj! self 'env env)
(set-obj! self 'name name)))
(get
(lambda (self name)
(--> self.env (get name))))
(set
(lambda (self name function)
(--> self.env (set name function))))
(toString
(lambda (self)
(string-append "#"))))

;; -----------------------------------------------------------------------------
(define (new-module name)
"(new-module name)

Create new empty module object with empty env."
(let ((env (new lips.Environment
(string-append "module-" (--> name (toLowerCase))))))
(new Module name env)))

;; -----------------------------------------------------------------------------
(module Math
(define (square_ x)
"(Math::square x)

Function square argument"
(* x x))
(export square_))

(import square_ Math)

(display (square_ 10))
(newline)
```

Start by comparing the proposed module and import macros with the R7RS define-library and import requirements. Use the Scheme example in the issue as the behavioral reference, then identify the interpreter entry points and tests that would need to cover library definition, exported names, and imports. Done means the feature is implemented for version 1.0 and its behavior is verified.

Written by the indexing model from the issue text.