Vundle manipulates plugin folders by `cd`-ing into them and calling git
via `call system(cmd)`. This doesn't work if GIT_DIR is set as a global
environmental variable (most commonly by a git hook). Since there is no
use case in which Vundle should respect GIT_DIR, this PR preemptively
precedes all git calls with `unset GIT_DIR; `. This makes the git calls
behave as expected without unsetting GIT_DIR in the environment beyond
vim.

- closes VundleVim#281

The command `silent pedit ...` was causing trouble if the user had `set
hidden`.  Now we `bdelete` the changelog buffer before editing it anew.

The variable is script local to autoload/vundle/scripts.vim since VundleVim#468.

These variables only occur in one file each.  By making them script local
variables this is "documented" in the code.  At the same time the global
namespace is polluted less.

Changed:
    g:bundle_names          -> s:bundle_names
    g:vundle_last_status    -> s:last_status
    g:vundle_log_file       -> s:log_file
    g:vundle_view           -> s:view

If it was loaded, unload the log buffer before editing it.  Otherwise the
editing command can "hang" if the user has `set hidden`.

This problem was originally discovered with the VundleChangelog command and
the analogous fix was applied in 7d9b10.  See github issue VundleVim#468 for more.

All global variables that are not part of the public API (mentioned in the
documentation) are turned into autoload variables.  This is intended to give
all global variables defined by Vundle.vim a common prefix.  The variable
g:default_git_proto is part of the public API and is therefor not changed.
This is the only exception.

Changed:
   g:bundle_dir            -> vundle#bundle_dir
   g:bundles               -> vundle#bundles
   g:updated_bundles       -> vundle#updated_bundles
   g:vundle_lazy_load      -> vundle#lazy_load
   g:vundle_log            -> vundle#log
Unchanged:
   g:default_git_proto

The setting of the default values for the autoload variables is moved out of
any function.  One reason being that these settings do not depend on the
argument of the function.  The second being that Vim will source the autoload
script if an undefined autoload variable is referenced and the file is
expected to define the variable (see :help autoload).

Plugins' names which contain '../', '$HOME', '%:h:h', '..\', etc.
can be dangerous.
Use a sensible whitelist for plugin names and prevent its expansion.

Saves a 301 redirect and removes a tad bit of confusion when `git
clone`-ing Vundle when installing.

buffers will not persist after they're closed.

incorrect URL and updated references to ':Bundle' commands to ':Plugin'
commands

This is done based on the simplified Chinese version at commit 232cb92.
Traditional Chinese is used by people in Taiwan, Hong Kong and Macao.

They are added by Notepad on M$ Windows.

A traditional Chinese version of the updated `README_ZH_CN.md`.

Fix typo

A traditional Chinese version of the updated `README_ZH_CN.md`.

* Updates readme to use github markdown checkmarks

According to this discussion VundleVim#713 this plugin is simply an example, but the example seems to consistently break the installation process.

If this is the case better to remove it.

Another example of it causing problems: VundleVim#784

See VundleVim#690

shell=/bin/bash needs to start with `set` in order to actually make vim+fish work correctly.