Contracts: Allow fine picking of end date

There is no way to specify a contract End Date to a given day. You set a Start Date and pick a number of months in Initial contract period, then the End Date is computed. But we have some contracts that doesn't matches this algorithm.

I think that implementing one of these options would enhance Contracts management:

• adding a dedicated End Date field
  • (which could be prefilled by JS according to Initial contract period, so that user experience would not change); or
• allowing to pick a Initial contract period in days instead of only in months.