[GNC-dev] budget.scm augmented to show ytd

[Christopher Lam]

for augmented budget report, which computes accumulated budget amounts
instead of periodic budget amounts.

https://github.com/christopherlam/gnucash/tree/maint-budget-refactor for
the whole repo

https://raw.githubusercontent.com/christopherlam/gnucash/maint-budget-refactor/gnucash/report/standard-reports/budget.scm
for the report (which may require a recent maint build)

adds a new option "YTD" which will display accumulated budget amounts (and
also accumulated budget less actuals)

the actuals remain period-specific.