renamed to use TranCodec instead of TranType
missed pubspec and readme from previous checkin
check for unregistered types only at toTranString()

only check for unregistered types when the call toTranString() is made.
do not enforce type checking before hand.
update version for previous checkin
add Types to core codecs
adding int and double codecs just for type support

all number instances will still be serialized just as num 'n' but double
and int are being registered to support transmission of their actual
Type.
update version number
add support for null values
tidy up some core type registrations
increment version number
allow  value pre processor at encode time
make tran-string delimiter a public constant
support dynamic Tran subtype creation
make registerCoreTypes() private
add foreach and clear to transmittable
refactored algorithm

made algorithm simpler and more consistent
reorganise code, and minor misc changes
give reference version constraint
Merge pull request #2 from 0xor1/dev

dev -> master