Lots of bad TAB eliminations.

I started from tabs that are not on the beginning of lines, and in
several places I did further cleanings.

If you're worried about knowing who wrote some code, for example, if you
get to this commit in "git blame", then note that you can use the "-w"
flag in many git commands to ignore whitespaces.  For example, to see
per-line authors, use "git blame -w <file>".  Another example: to see
the (*much* smaller) non-whitespace changes in this (or any other)
commit, use "git log -p -w -1 <sha1>".

original commit: 672910f27b856549ad08d38832b6714edf226c8e

collects/rackunit/scribblings/check.scrbl

@@ -184,7 +184,7 @@ The following check fails:
 @defproc[(check (op (-> any any any))
                 (v1 any)
                 (v2 any)
-		(message string? ""))
+                (message string? ""))
          void?]{
 
 The most generic check.  Succeeds if @racket[op] applied to
@@ -233,13 +233,13 @@ misspelling errors:
 
 @defproc*[([(make-check-name (name string?)) check-info?]
            [(make-check-params (params (listof any))) check-info?]
-	   [(make-check-location (loc (list/c any (or/c number? #f) (or/c number? #f) 
+           [(make-check-location (loc (list/c any (or/c number? #f) (or/c number? #f) 
                                                   (or/c number? #f) (or/c number? #f))))
             check-info?]
-     	   [(make-check-expression (msg any)) check-info?]
-	   [(make-check-message (msg string?)) check-info?]
-	   [(make-check-actual (param any)) check-info?]
-	   [(make-check-expected (param any)) check-info?])]{}
+           [(make-check-expression (msg any)) check-info?]
+           [(make-check-message (msg string?)) check-info?]
+           [(make-check-actual (param any)) check-info?]
+           [(make-check-expected (param any)) check-info?])]{}
 
 @defproc[(with-check-info* (info (listof check-info?)) (thunk (-> any))) any]{
 

collects/schemeunit/gui.rkt

@@ -1,3 +1,3 @@
-#lang racket
+#lang racket/base
 (require rackunit/gui)
 (provide (all-from-out rackunit/gui))

collects/schemeunit/text-ui.rkt

@@ -1,3 +1,3 @@
-#lang racket
+#lang racket/base
 (require rackunit/text-ui)
 (provide (all-from-out rackunit/text-ui))