EIP158 & 160 Hardfork

This commit implements EIP158 part 1, 2, 3 & 4

1. If an account is empty it's no longer written to the trie. An empty
  account is defined as (balance=0, nonce=0, storage=0, code=0).
2. Delete an empty account if it's touched
3. An empty account is redefined as either non-existent or empty.
4. Zero value calls and zero value suicides no longer consume the 25k
  reation costs.

params: moved core/config to params
Signed-off-by: NJeffrey Wilcke <jeffrey@ethereum.org>

Topic discovery bugfix

cmd: add swarm command line tools

cmd/geth: reinstate dropped --cache flag

These accessors were introduced by light client changes, but
the only method that is actually used is GetNumberU64. This
commit replaces all uses of .GetNumberU64 with .Number.Uint64.

archiveUpload did not handle absolute paths correctly. Fix it by using
the basename and ensure that uploads can be tested using -n.

This commit adds support for creating Windows installers to ci.go