added Container spec deserialization
Add missing const to MVM_string_ascii_decode*()
version cleans up in serialization.c
Add Invocation spec deserialization
Add missing MVMROOT
sc_elems comes from root_objects.
nqp::deserialize needn't have a result reg.
Make sure serialize doesn't run into GC issues.

We now pass the first 3 tests in serialization/01-basic.t.
Implement serialize for a few basic REPRs.
Add some BOOT* into the core SC.
nqp::scsetobj should push STable if unowned.
Add shift repr convenience funcs.
Fix BOOTHash serialization.
Merge branch 'master' into static-repr

Conflicts:
	src/6model/bootstrap.c
	src/6model/reprs/P6int.c
	src/6model/reprs/P6num.c
	src/core/args.c