add Previm and window management

sources_non_forked/previm/plugin/previm.vim

@@ -0,0 +1,32 @@
+" AUTHOR: kanno <akapanna@gmail.com>
+" License: This file is placed in the public domain.
+
+if exists('g:loaded_previm') && g:loaded_previm
+  finish
+endif
+let g:loaded_previm = 1
+
+let s:save_cpo = &cpo
+set cpo&vim
+
+function! s:setup_setting()
+  augroup Previm
+    autocmd! * <buffer>
+    if get(g:, "previm_enable_realtime", 0) ==# 1
+      " NOTE: It is too frequently in TextChanged/TextChangedI
+      autocmd CursorHold,CursorHoldI,InsertLeave,BufWritePost <buffer> call previm#refresh()
+    else
+      autocmd BufWritePost <buffer> call previm#refresh()
+    endif
+  augroup END
+
+  command! -buffer -nargs=0 PrevimOpen call previm#open(previm#make_preview_file_path('index.html'))
+endfunction
+
+augroup Previm
+  autocmd!
+  autocmd FileType *{mkd,markdown,rst,textile}* call <SID>setup_setting()
+augroup END
+
+let &cpo = s:save_cpo
+unlet! s:save_cpo