Fix some references

lens/applicable.rkt

@@ -3,7 +3,7 @@
 (provide (all-from-out "main.rkt"))
 
 (require "main.rkt"
-         (only-in "core/base.rkt" use-applicable-lenses!))
+         (only-in "base/base.rkt" use-applicable-lenses!))
 
 (module+ test
   (require rackunit))

lens/hash.rkt

@@ -3,7 +3,7 @@
 (provide hash-ref-lens)
 
 (require fancy-app
-         "core/main.rkt")
+         "base/main.rkt")
 
 (module+ test
   (require rackunit))

lens/main.rkt

@@ -9,7 +9,7 @@
 (provide
  (except-out
   (all-from-out
-   "core/main.rkt"
+   "base/main.rkt"
    "list/main.rkt"
    "syntax.rkt"
    "syntax-keyword.rkt")