Add support for unicode plugin

This commit adds support for the :UnicodeTable of https://github.com/chrisbra/unicode.vim

autoload/airline/extensions/unicode.vim

@@ -0,0 +1,22 @@
+" MIT License. Copyright (c) 2013-2016 Bailey Ling.
+" vim: et ts=2 sts=2 sw=2
+
+if !get(g:, 'loaded_unicodePlugin', 0)
+  finish
+endif
+
+function! airline#extensions#unicode#apply(...)
+  if exists(":UnicodeTable") == 2 && bufname('') ==# 'UnicodeTable'
+    call airline#parts#define('unicode', {
+          \ 'text': '[UnicodeTable]',
+          \ 'accent': 'bold' })
+    let w:airline_section_a = airline#section#create(['unicode'])
+    let w:airline_section_b = ''
+    let w:airline_section_c = ''
+    let w:airline_section_y = ''
+  endif
+endfunction
+
+function! airline#extensions#unicode#init(ext)
+  call a:ext.add_statusline_func('airline#extensions#unicode#apply')
+endfunction