:bug:Fix delete with 'G' motions

This is an attempt at fixing #325.
The changes fixes delete with the G motions, but it breaks some specs.
What do you guys think?

dG from line 4 (eof)
![dv-dg](https://cloud.githubusercontent.com/assets/2568174/3422302/0b548f06-ff2b-11e3-8df9-3b8c0150adfe.gif)

d2G from line 4 (backward)
![dv-d2g](https://cloud.githubusercontent.com/assets/2568174/3422299/0b4f3484-ff2b-11e3-9e79-a39b3e7d32c0.gif)

d6G from line 4 (forward)
![dv-d6g](https://cloud.githubusercontent.com/assets/2568174/3422300/0b533b24-ff2b-11e3-8268-ed99ef92a80b.gif)

d4G from line 4 (same line)
![dv-d4g](https://cloud.githubusercontent.com/assets/2568174/3422301/0b53884a-ff2b-11e3-9bc7-af4e3a71c70e.gif)


# Broken Specs
## Operators
  - the d keybinding
    - when followed by a d
      - it deletes the current line and exits operator-pending mode
  
  - the c binding
    - when followed by a c
      - it deletes the current line and enters insert mode
    - when the cursor is on the last line
      - it deletes the line's content and enters insert mode on the last line
  
  - the > keybinding
    - on the last line
      - when followed by a >
        - it indents the current line
        
  - the = keybinding
    - when used in a scope that supports auto-indent
      - when followed by a repeating =
        - it autoindents multiple lines at once
        
  - the . keybinding
    - it composes with motions

## VimState
  - marks
    - it real (tracking) marking functionality
This makes `dG` use the default `count=@editor.getLineCount()` from `MoveToLine`.