* src/validate/ValidStateMonitor.js (mergeFailures):
Another error on a field that previously failed will no longer overwrite the
previous failure, which caused issue when the causes changed (leaving fields
potentially unfixed).
* test/validate/ValidStateMonitorTest.js: Respective tests added.
* src/validate/Failure.js (__construct): Takes an array of causes.
(getCauses): Now returns an array of causes.
* src/validate/ValidStateMonitor.js: Recognize fixes on array of causes.
* test/validate/FailureTest.js: Updated
* test/validate/ValidStateMonitorTest.js: Updated
This maintains BC with the old string-based system.
* src/validate/ValidStateMonitor.js (_getCause): Added.
(detectFixes): Consider failure cause if available when checking for fixes.
This is to facilitate a transition to Failure without a BC break.
* test/validate/ValidStateMonitorTest.js: Ensure that replacing messages
with Failure will continue to operate as expected.
The intent is to ultimately replace ClientFieldValidator with this and
individual validators that interact with it.
* src/validate/ValidStateMonitor.js: Added
* test/validate/ValidStateMonitorTest.js: Added