Changed math to numbers in the sbt build file.
Added some tests for be === stack depth, which already passed, and fixed two
Specs that had been accidently made to be unable to instantiate.
Fixed some bugs in the PosSpec test, which sbt is not running currently, and
added a est and code for widening conversions from Pos to Int, Long, Float, Double,
Poz, LPoz, FPoz, and DPoz.