WNote - Note management updated

- WNote::raise() can be used to trigger a note later in the script
- Note stack is now indexed by Note's code (to ensure a note's code is
unique)
- Comments updated
Updated how main view is rendered

- WView::prepare() revised to render()
- WResponse cleaned up
- Themes main file: don't use {include {$include}} anymore but directly
{$include} (temporary)