vim: replace <leader> with <localleader>

http://learnvimscriptthehardway.stevelosh.com/chapters/11.html
vim: fix auto command declarations

http://learnvimscriptthehardway.stevelosh.com/chapters/14.html
vim: typo
vim: new keymappgins

From: Steve Losh, https://bitbucket.org/sjl/dotfiles/overview
vim: improve the "custom commands" section

 * remove unnecessary functions
 * improve the Transliterate function (now it's capable for working with latin1
   charset)
 * reorder "Close Omni preview" auto command (it is not a macro or a
   custom command)
vim: syntax highlighting for nginx config files