gnucash maint: [trep-engine] upgrade to include 'balance brought forward'

[Christopher Lam]

Updated	 via  https://github.com/Gnucash/gnucash/commit/741eb480 (commit)
	from  https://github.com/Gnucash/gnucash/commit/0f4265d9 (commit)



commit 741eb480168f1ecb8b10b4b61240a565be87bdad
Author: Christopher Lam <christopher.lck at gmail.com>
Date:   Mon Jan 6 22:03:53 2020 +0800

    [trep-engine] upgrade to include 'balance brought forward'
    
    This fairly complex-looking change is actually simple.
    
    default-calculated-cells is redefined so that the running-balance
    column has a custom subheading renderer. The subheading renderer was
    formerly used solely for the account->friendly-debit/credit-string
    renderer, and is now upgraded to handle hard-coded symbols.
    
    If the friendly-heading-fn is a symbol 'bal-bf, it'll print the
    split->account->balance at begindate.
    
    Other columns may also be upgraded for novel subheading renderers. No
    forward/backward compatibility issues are expected at all. This change
    looks complex because the begindate is not available to
    make-split-table and has to be passed on as an argument to be
    available for use, and the subheading-renderer will test whether to
    display the friendly-fn-renderer at a later stage than previously.



Summary of changes:
 gnucash/report/report-system/trep-engine.scm | 68 ++++++++++++++++------------
 1 file changed, 40 insertions(+), 28 deletions(-)