allow StructureDescriptionImpl to simultaneously a) register itself as the type handler of record for the structure, and b) derive from StructureDescription<Struct> so that addParent() works.  There are now tests for both of these requirements.
Date: added support for iso8601 week dates, milliseconds and timezones to the parser
fixed method call
Date: removed methods obsoleted by previous commit
Date: tuned "expectFixedWidthInt" to tolerate a minimum length
Date: minutes and seconds are indexed from 0
added operators to perform arithmetic with dates and time periods
Merge branch 'master' of github.com:datacratic/soa
added back in old parseIso8601 function that can deal with NaD and Inf values
Date: test input string for exceptional values and removed Date::parseIso8601Time
disabled obsolete and failing test
json parsing: enable instantiation of NULLID Id instance when parsing a "null" value
Date: enable the printing of milliseconds when using iso 8601 format
Merge branch 'Id-json-null-support'
declare StructureDescription as value kind "STRUCTURE"
Merge pull request #47 from datacratic/structures-as-structures-fix

declare StructureDescription as value kind "STRUCTURE"
Merge branch 'master' into sched-exp