VM: Three new special objects added to keep track of the builds version number, git label and compilation time respectively. The info is exposed in the system:version-info word and also shown in the banner during startup.

Conflicts:
	Nmakefile
	basis/ui/tools/listener/listener.factor
	core/alien/strings/strings.factor
VM: renamed version and git-label to vm-version and vm-git-label.
VM: using make vocab instead of consecutive appends
GNUmakefile, factor.cmd: Update versions to 0.98
ffi: test functions for bug #1021

Conflicts:
	vm/ffi_test.c
	vm/ffi_test.h

Note: Let's add tests in basis/compiler/tests/alien.factor for this.
VM: debug code which memsets the resetted space