Added a BNF grammar file describing the Ledger data format.
Added a BNF grammar file describing the Ledger data format.

afh/ledger,duncanmortimer/ledger,jwakely/ledger,afh/ledger,jwakely/ledger,afh/ledger,ledger/ledger,jwakely/ledger,paulbdavis/ledger,duncanmortimer/ledger,duncanmortimer/ledger,paulbdavis/ledger,jwakely/ledger,ledger/ledger,jwakely/ledger,duncanmortimer/ledger,ledger/ledger,jwakely/ledger,duncanmortimer/ledger,duncanmortimer/ledger,duncanmortimer/ledger,ledger/ledger,paulbdavis/ledger,paulbdavis/ledger,paulbdavis/ledger,jwakely/ledger,ledger/ledger,afh/ledger,afh/ledger,paulbdavis/ledger,paulbdavis/ledger