treefromthesky in createcanopy.R

[VincyaneBadouard]

• code
• test
• document (V0)
• Sylvain's check (code)
• Geraldine check (doc)

[sylvainschmitt]

• I do not like the name of the function, I would rather use a sober name (e.g. getwrown). But maybe it's just my point of view and we should discuss with Géraldine. So you can skip this remark.
• You lack a return in the code. It returns the last object crown but it is always better to define it explicitly.

Everything else is great, congrats!