Added save_xxx snippets

Saving some values in temprary variables is common process in writing
Vim script.  I made snippets for them for DRY.

Added save_xxx snippets
- save_pos
- save_register
- save_options

Followings are examples of them.

    let pos_save = getpos('.')

    call setpos('.', pos_save)

    let save_reg_g = getreg('g')
    let save_regtype_g = getregtype('g')

    call setreg('g', save_reg_g, save_regtype_g)

    let selection_save = &selection
    let &selection =

    let &selection = selection_save

autoload/neosnippet/snippets/vim.snip

@@ -183,4 +183,25 @@ abbr    lua <<EOF | EOF
     ${0}
     EOF
 
+snippet save_pos
+options head
+abbr    use pos save
+    let pos_save = getpos('.')
+    ${0}
+    call setpos('.', pos_save)
 
+snippet save_register
+options head
+abbr    use register save
+    let save_reg_$1 = getreg('${1}')
+    let save_regtype_$1 = getregtype('$1')
+    ${0}
+    call setreg('$1', save_reg_$1, save_regtype_$1)
+
+snippet save_option
+options head
+abbr    use option save
+    let $1_save = &${1}
+    let &$1 = ${2}
+    ${0}
+    let &$1 = $1_save