Correct cite and ref pattern to include magic flag

See complete.vim, line 115, where the magic flag is prepended to the pattern. This is good to know if one uses an autocompletion plugin such as NeoComplete to tell it when to invoke LatexBox completion, for example:

" Use LatexBox OmniCompletion
" defaults from documentation + assumed \magic option
let s:LatexBox_cite_pattern = '\c\\\a*cite\a*\*\?\(\[[^\]]*\]\)\_\s*{'
let s:LatexBox_ref_pattern  = '\C\\v\?\(eq\|page\|[cC]\)\?ref\*\?\_\s*{'

let g:neocomplete#sources#omni#input_patterns.tex = '\m' .
						  \ '\('.s:LatexBox_ref_pattern.'\)' . '\|' .
						  \ '\('.s:LatexBox_cite_pattern.'\)'
" }