envfile now respects provided directory name
in read item list, permit absence of vars from env (assume not distributed)
0s for halo info for non-distributed dimensions in exchange calls
forbid sms$ignore in serial regions (not sure if this will stick)
update TODO
add Subscript#lower & Subscript#upper
work on global start/stop, variable name in SMS_Exchange#translate
don't send 'free' argument to ppp for free-form tests
update TODO
differentiate standalone vs server-mode ppp/pppc arguments
work on Allocate_Object#translate w.r.t. derived vs primitive types