[8.0] Porting l10n_it_corrispettivi

[shakin89]

This is my first attempt to port a module to v 8.0

[coveralls]

Coverage decreased (-6.81%) when pulling fe5cfe9 on shakin89:8.0 into 7e8ae7c on OCA:8.0.

[coveralls]

Coverage decreased (-6.81%) to 58.96% when pulling b0bdad1 on shakin89:8.0 into 7e8ae7c on OCA:8.0.

[eLBati]

Thanks @shakin89
I see you started from l10n_it_corrispettivi version contained in 8.0 branch, but it is outdated. You should start porting from 7.0 branch.
See the diff between 7.0 version and your version:
https://gist.github.com/eLBati/d0b190881f72b356f2a2
As you can see, you removed some improvements made on 7.0 which must be kept (like from . import account)

So, please copy the 7.0 version of the module to a new branch and apply your commits on it.
Thanks

[shakin89]

Ok, i've ported the improvement made in 7.0 version, i've compared all the files and aligned the 7.0 version to this one.

[coveralls]

Coverage decreased (-6.81%) to 58.96% when pulling 4a92401 on shakin89:8.0 into 7e8ae7c on OCA:8.0.

[coveralls]

Coverage decreased (-6.81%) to 58.96% when pulling 76fec06 on shakin89:8.0 into 7e8ae7c on OCA:8.0.

[eLBati]

This gives conflicts and should be rebased

[eLBati]

@shakin89 chiuderei questa PR per continuare il tuo lavoro sulla #230 e sistemare le ultime cose per fare il merge.
Fammi sapere se OK per te