Better placement of the minimap in the pane and remove editor/minimap overlap

**IMPORTANT: This is a work in progress and currently many features are broken, so it's not ready to merge yet.**

The main goal of this branch is to end with a minimap that is the real reflect of the editor view (with soft wraps) and to have the minimap positioning behaving like the ST one, taking a percentage of the pane and appearing in a side gutter that push the buffer content inside the pane.

What's working now: 

  - I have the minimap generation process handle soft wrapping, in the process the generation time was cut by 3 or 4.
  - I have the pane gutter in place with the scroll view and scrollbar sized and positioned accordingly.

What isn't working :

  - The minimap overlay is broken.
  - The minimap scrolling still doesn't goes all the way to the bottom, leaving some lines hidden even when reaching the bottom line.

Clicking on the minimap seems to not have been broken much but I can't guarantee that it doesn't.