This adds "require" functionality which allows invariants
to be checked after processing transactions using a simple,
terse interface. Also adds more comprehensive test coverage
for the framework itself, verifying that the more sophisticated
language constructs work in all ways.
All functions and classes have been split up into individual
files which may be included a-la carte, or accessed through
a single convenience header <ripple/test/jtx.h>
* Move, rename all sources
* Put everything in the jtx namespace
* Add sendmax funclet
* Rename funclet to paths
* Correctly set input issue and destination amount in path
* Conditionally invoke funclets using is_call_possible
* Add any() function means "any currency they will accept"
* Add None, none modifiers on amounts to mean "no amount"
* Add require conditions to JTx
* Add Env::require variadic condition checker
* Add le, rename some items for consistency
* Add require functors, balance, flags, nflags
* Add require functors lines, owners, offers, tickets
* Add ticket example of extending the system
* Add noripple modifier for funding accounst
* Add Env::st to parse Json into STTx
* Add tests to ensure correctness of fund()
* Add virtual Env member hooks
* Add Env::balance
* Add Env::seq
* Add PrettyAmount
* Add all container Account support
* IOU and XRP return PrettyAmount amounts
* IOUs print the issuer's name instead of base58
* Fix int and double conversions to XRP
* Fix autofill of Env::fund with noripple
