Add support for spellchecking with a custom dictionary.

To use:

  1. Install aspell
  2. waf spell <list of files>
     * waf spell mydoc.rst
     * waf spell *.rst

This uses a custom dictionary stored in common/spell/dict/.  We should add all
RTEMS and programming terms to this to ensure we are consistent.

Amar.

networking/wscript

@@ -2,7 +2,7 @@ from sys import path
 from os.path import abspath
 path.append(abspath('../common/'))
 
-from waf import cmd_configure, cmd_build
+from waf import cmd_configure, cmd_build, spell, cmd_spell
 
 def configure(ctx):
 	cmd_configure(ctx)