why:
subsequent development will compile sources as main without setting
the vm2_enabled flag. also, the doc generator would fail an vm2 without
setting the flag for the vm2 files.
why:
new name forks_list.nim file name matches additional documentation
file names.
details:
v2forks.nim remains a hollowed out shell serving as interface file.
why:
these files provide part of the externally accessible interface
provided by vm_types*.nim. so the new filename indicates that the
source code belongs to vm2 (rather than vm).
Jordan Hrycaj