* Fixed some spelling/language errors in mysqlcheck
* Added some more information in mysql -client internal help.


Docs/manual.texi:
  Added a note about bug fix in my_getopt to changelog section.
client/mysql.cc:
  Added some information in mysql -client internal help.
client/mysqlcheck.c:
  Fixed some spelling / language errors.
mysys/my_getopt.c:
  Fixed a bug in my_getopt:
  --skip-external-locking didn't work and the same bug affected some
  other similar options. 
  
  After fix it is now possible to use the following:
  
  --external-locking                -> enable
  --external-locking=0              -> disable
  --external-locking=1              -> enable
  --skip-external-locking           -> disable
  --skip-external-locking=0         -> enable
  --skip-external-locking=1         -> disable
  --enable-external-locking         -> enable
  --enable-external-locking=0       -> disable
  --enable-external-locking=1       -> enable
  --skip-external-locking=garbage   -> disable
  --enable-external-locking=garbage -> enable
  
  This works now with all options that are boolean type and which
  name doesn't start with --skip- or --enable-.