update dox for waf --check

doc/build.txt

@@ -36,7 +36,7 @@ The resulting binaries are placed in build/<debuglevel>/srcpath.
 
 Other waf usages include:
 
- 1. ./waf check
+ 1. ./waf --check
     Runs the unit tests
 
  2. ./waf --doxygen

doc/main.h

@@ -27,8 +27,8 @@
  * ns-3 requires Doxygen version 1.5.4 or greater to fully build all items,
  * although earlier versions of Doxygen will mostly work.
  * 
- * Type "./waf check" followed by "./waf --doxygen" to build the documentation.
- * There is a program that runs during "./waf check" that builds pieces of
+ * Type "./waf --check" followed by "./waf --doxygen" to build the documentation.
+ * There is a program that runs during "./waf --check" that builds pieces of
  * the documentation through introspection.  The doc/ directory contains
  * configuration for Doxygen (doxygen.conf and main.txt).  The Doxygen 
  * build process puts html files into the doc/html/ directory, and latex 

doc/manual/new-models.texi

@@ -205,7 +205,7 @@ add this to @code{src/common/wscript}.  It is really just a matter
 of adding the .cc file to the rest of the source files, and the .h
 file to the list of the header files. 
 
-Now, pop up to the top level directory and type "./waf check".  You
+Now, pop up to the top level directory and type "./waf --check".  You
 shouldn't have broken anything by this operation.
 @subsection include guards
 Next, let's add some 

doc/release_steps.txt

@@ -6,12 +6,12 @@ Steps in doing an ns-3 release
    - revise and check in RELEASE_NOTES
    - DO NOT change VERSION at this time
    - confirm that Doxygen builds cleanly and without warnings
-     (./waf check; ./waf --doxygen), and check in any necessary changes 
+     (./waf --check; ./waf --doxygen), and check in any necessary changes 
    - ensure no regressions (./waf --regression)
 3. ./waf configure; ./waf dist
    - this will create an ns-3-dev.tar.bz2 tarball
    - this will also create a ns-3-dev-ref-traces.tar.bz2 tarball
-4. test dev tarball on release platforms (waf check and maybe some other 
+4. test dev tarball on release platforms (waf --check and maybe some other 
    scripts)
 5. once you are happy with the tarball, tag ns-3-dev and ns-3-dev-ref-traces
    - hg tag "ns-3.x"

doc/tutorial/getting-started.texi

@@ -456,10 +456,10 @@ but now you know how to change the configuration and build optimized code.
 
 @cindex unit tests
 You can run the unit tests of the @command{ns-3} distribution by running the 
-``check'' command,
+``--check'' option,
 
 @verbatim
-  ./waf check
+  ./waf --check
 @end verbatim
 
 You should see a report from each unit test that executes indicating that the

doc/tutorial/in-process/introduction.texi

@@ -562,7 +562,7 @@ The build system is now configured and you can build the debug versions of
 the ns-3 programs by simply typing,
 
 @verbatim
-  ./waf check
+  ./waf --check
 @end verbatim
 
 You will see many Waf status messages displayed as the system compiles.  The