The last panel now fills all the remaining space of the viewport

Consequently,
- It may be wider than its max-width
- It may be smaller than its min-width

This prevent unwanted behaviour where the user was obliged to scroll when the las panel has a min-width greater than the width of the viewport. Also prevent the case where the last panel was smaller than the remaining space, because of its max-width.
[Generating dist files]
Merge pull request #64 from Evaneos/last-panel-full-screen

The last panel now fills all the remaining space of the viewport