Remove remap of H & L

I never use them for start and end of like (I use | and $), and the
default H & L for top and bottom of screen is more useful to me.
Add edit vimrc and source vimrc

Ability to edit the vimrc and source it, making changes on the fly
easier.

http://ctoomey.com/posts/an-incremental-approach-to-vim/
Add JavaScript syntax libraries bundle

This supports multiple JavaScript libraries, jQuery, CoffeeScript, etc.

https://github.com/othree/javascript-libraries-syntax.vim
Remove folding settings

These settings are already covered in the vimrc so they're not really
needed in the gvimrc.
Make the remap work by loading last

This has been commented as not working for ages, finally get around to
making it work with the autocmd.
Add advanced help navigation

pressing enter in help opens the link in a new buffer, backspace goes
back to the previous buffer.

Documented here:
http://ctoomey.com/posts/an-incremental-approach-to-vim/
Remove nerdtree tabs plugin

As I'm no longer using nerdtree, there's no need for this plugin. It was
causing problems with closing buffers, as it was closing all of them on
:bd when I only wanted one deleted.