Add description of l10n to HACKING.
Add description of l10n to HACKING.

* HACKING (Localization): 
   New section describing l10n from the programmers POV.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion