Allow to remove an asset before its full depreciation

The changes : 
- New account on asset category, used only when we remove an asset before it is fully depreciated
- add a button when an asset is opened to allow the antipated removal

If the user choose to do so, it will remove all depreciation lines which date is after the removal  date.
It will change the depreciation line corresponding to the removal date to adjust the amount and the date if we the boolean 'prorata temporis' is matched. (Else, it will remove it). Then validate automaticaly this modified depreciation line so it creates its account.move.line.
Finally, it will creates 3 removal account move line. The residual amount which could not be depreciated goes to the new account.

Note, the early removal date have to be after the last posted entry and during the first non-posted entry.

I make a merge proposal here so you can tell me what you think and ask if it is not clear.
I would gladly take your advices into consideration.
If you think merging this PR with yours would delay the merge into OCA branch, then I can propose this merge to OCA directly so it won't impact your PR.

Anyway, I would like to have your opinion.