CogVM source as per VMMaker.oscog-eem.3794

First, the previous commit also included
VMConstruction-Plugins-OSProcessPlugin.oscog-eem.83

Cleanup primitiveSendSigkillTo to use #=, not #==,
and methodReturnInteger: instead of pop: & pushInteger:

Oops! now SpurMemoryManager>>lowSpaceThreshold: invokes itself it can't
be inlined and collides with SpurMemoryManager>>lowSpaceThreshold. So
rename to SpurMemoryManager>>setLowSpaceThreshold: and type its argument
to get the lowSpaceThreshold var to be typed correctly.