feat(hr.payslip): compute year to date days and add into payslip inputs
Add an input that computes days from year to date. The new input can be use with code YTD
If contract start date if before the first day of the year the YTD input reflects the actual
number of days elapsed from the first day of the year to the last day included on payslip.
If contract date start is after the first day of the year then the YTD input reflects the
number of days elapsed from the contract start date to the last day included on payslip.
Also rewrite the salary rules used to pay an employee when finishing a job relation:
- End relation payment (Finiquito)
- Vacations
- Christmas bonus