Change initialization syntax to support other parallelism sources.
Fix bugs affecting persistent files.

Convert	3rd argument of	require() to parallelism type (bsp, fj,	user)
  - Update reference manual

ems.cpp:
  Test	for integer overflow in faa and promote to float, like JS does.
  Fix bug which	incorrectly clobbered tag types	when 'persistent' data is used.

index.js:
  Convert while	loop to	do loop
  Add doDataFill argument to explicitly	indicate whether data initialization	should occur