FILE() now supports line-mode and writing (altering) files.

(closes issue #16461)
 Reported by: skyman
 Patches: 
       20100622__issue16461.diff.txt uploaded by tilghman (license 14)
 Tested by: tilghman
 
Review: https://reviewboard.asterisk.org/r/737/


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@276114 65c4cc65-6c06-0410-ace0-fbb531ad65f3