fix shadowing declarations

"non-inline namespace cannot be reopened as inline"

use std::atomic, though with operator->() for now, since that can only be overriden with a member function

use atomic<> for dir pointer in an inode

crange and range "defined as a class here but previously declared as a
struct"

"non-inline namespace cannot be reopened as inline"

Conflicts:
	vm.cc

Conflicts:
	crange.cc
	kernel.h

Much room for cleanup

Hopefully this is enough to prevent all the random connections to
josmp.

..to use clang, define USE_CLANG in config.mk.

use a virtual do_gc() function instead of virtual destructor; gives more freedom in choice of memory allocation