Documentation Update.

* Add modelines to all code/doc files excluding README.md.  The modeline used is: `" vim: set expandtab sts=2 ts=2 sw=2 tw=78 norl:`
* Rename links with /vundle to /Vundle.vim, seems to confuse some people with redirect.
* Remove duplicates from Quickstart, add example of `name` flag.
* Add link to Tips page by @Lucc .
* Change help maintain vundle link directly to the new one.
* README.md line number links updated.

Note: Users with bundle/vundle need to rename vundle to Vundle.vim to use test files. Vundle will continue to function otherwise.

Fixes #413.
Fixes #438.
Treat changed remotes as new plugins

If one had this plugin:

Plugin 'foo/bar'

And now switches to another one with the same name:

Plugin 'baz/bar'

Recognise this scenario and replace the old plugin with the new one,
rather than silently assuming they are the same.

Fixes #367 #48 #183 #400
Check name collissions