Make these all go through .open() and pass in args to control the
behaviour. Deprecate the old `openSplit`, `openVSplit` and
`openInNewTab` methods and make them private.

This makes the API a lot cleaner - it was getting pretty messy in this
regard.

This allows users to specify whether each regex in NERDTreeIgnore should
apply to only files or only dirs.

This fixes #89.

First, set the tree parts regex appropriately depending on
g:NERDTreeDirArrows.

Second, fix an edge case when trying to edit a file like +foo where the
+ meant 'foo' was being interpreted as an arg to the :edit cmd

this gives users a chance to filter out nodes using whatever logic they
please

Just call these functions directly at the bottom of the nerdtree script.
This simplifies things and fixes #99.

It seems that some versions of vim done like the syntax of:
    function("foo")()

so refactor it slightly.

stayInCurrentTab fix

dont display quickhelp for a mapping if there is no text to display -
this prevents all the default mappings from being displayed under the
"custom mappings" section.

Add "scope" to it. This allows the user to specify that keymaps should
 apply to files/directories/bookmarks or everything. This will reduce
the amount of 'if empty(node)' checks that are done

create s:setCommonBufOptions() with the previously duplicated parts of
s:initNerdTreeInPlace() and s:createTreeWin()

Add nolist to buffer options.

Added new options in the file system menu

this breaks the highlighting of the nerdtree buffer, and seems dodgy

Note that for directories, there is a trailing slash

Spelling

- Reveal In Finder
 - Open with system editor
 - Quicklook

Current only when using MacVim under MacOSX

Remove the NERDTreeStopInsert option and always activate the
functionality. If, later on, it becomes apparent that some people might
not want this functionality then we can re-add the option, but in the
meantime, simplify things by removing the option.

wycats's "disallow insert mode"

An explanation from vguerci@github:

Insert mode can be entered in nerdtree not sure the exact sequence / reason, but i guess that involve using mouse (sounds weird, a bug?) :

- open nerdtree, select a buffer, enter insert mode in buffer.
- select nerdtree buffer with mouse, you're in insert mode.

...then you can easily get E21, E382 errors.
Not a big deal but that can happen, if you use mouse... (which I don't)
(reproduced this on latests macvim (vim 7.3.260) from terminal (vim) or macvim)

3bb112d916

when copying a file outside the current tree root, {} is returned by
TreeFileNode.copy() so try to reposition the cursor