Set filetype unconditionally and after defining mappings.

Because NERD_Tree sets the filetype in its buffer, it's tempting to hook into the FileType event in order to customize it. Unfortunately, the buffer-local mappings are only defined _after_ setting the filetype, so one cannot un-/redefine them via this mechanism. (I know there are config variables and an API for that, but one may have other unforeseen uses.)
Therefore, swap the order and set the filetype last. Also, use :setlocal filetype= instead of :setfiletype. In the (remote) chance that a custom filetype detection mistakenly sets a filetype for the NERD_Tree buffer, the :setfiletype would be without effect, but we want to force the filetype (for the special syntax) here.
Fix typo Casade to Cascade
Add correspoding close action to cascade open single child dir
Fixed typo in NERD_tree.txt
Fix help mistake
Create nested parent directories as needed

Allows the user to create or copy a nested node
in a single step with ma or mc, recursively
creating nested parent directories if needed, and
without throwing any errors if they already exist.

[Finishes #163, #34]
Fix typo
Add option to respect wildignore
correct invalid reference to MenuController

I found an error when I tried to use [git_menu.vim](g:NERDTreeMenuController):

```
Error detected while processing function nerdtree#invokeKeyMap..91..90..<SNR>52_showMenu..65..82:
line    2:
E121: Undefined variable: s:MenuController
E15: Invalid expression: s:MenuController.New(self.children)
line    3:
E121: Undefined variable: mc
```

I searched the line at which it happened
then, I found that `s:MenuController` is not defined in  `menu_item.vim` but in menu_controller.vim .
So I corrected the name to refer to MenuController.
Issue 315 - Incorrect buffer deleted on file delete
Use pathogen.vim Helptags command in README file
Add flag to disable/enable bookmark sorting

The bookmarks are normally sorted, however with a newly introduced
flag this can be disabled.
Support space in path when renaming
Option for mixing dot files when sorting

NERDTree can now optionally ignore the dot at the beginning of hidden
filenames for sorting to show them next to normal files if
`g:NERDTreeSortHiddenFirst` is set to 0.  (By default it's set to 1 to
preserve the current behavior.)  This is just like what GNU ls does when
`LC_COLLATE` environment variable is set to `en_US`.
Merge pull request #340 from netj/sort-hidden-first-option

Option for mixing dot files when sorting
Merge pull request #338 from trkoch/spaces-umlauts

Support spaces and umlauts in path
Merge pull request #331 from jinnko/add-bookmarks-sort-flag

Add flag to disable/enable bookmark sorting
Merge pull request #326 from migueldvb/docs

Use pathogen.vim Helptags command in README file
Merge pull request #274 from an1zhegorodov/master

Fix help mistake
Merge pull request #295 from DanielleSucher/create_parent_directories_as_needed

Create parent directories as needed when creating or copying nested nodes