Support absence of wallet (pwalletMain==NULL) in several locations,
notably RPC.

Conflicts:
	src/bitcoinrpc.cpp
	src/init.cpp
	src/rpcmining.cpp
	src/rpcwallet.cpp

Rebased-from: 541a7fcd515a27ebaa3ae5f1a9a698dab3db6ead
Rebased-by:   Warren Togami <wtogami@gmail.com>
RPC validateaddress: test pwalletMain for NULL (no-wallet mode)

Conflicts:
	src/rpcwallet.cpp

Rebased-from: b878f6a92436e3facd700e2e10c04f541cd6421b
Rebased-by:   Warren Togami <wtogami@gmail.com>
init.cpp: cosmetic indent changes, preparing for no-wallet mode

Conflicts:
	src/init.cpp

Rebased-from: 520cc05b89aae5fed155482d5fa66b4290487d55
Rebased-by:   Warren Togami <wtogami@gmail.com>
Add -disablewallet option, to disable wallet support (and BDB)

Conflicts:
	src/init.cpp

Rebased-from: 5d4f3a1f0cbdf52257b41ea09d175c0018ad9434
Rebased-by:   Warren Togami <wtogami@gmail.com>