Cherry-picked 8259baf3dfc162e9925aa1e70bdf6ccf891e78c1

Fix TITAN scanning regression; resolves #1071

Conflicts:
	libraries/blockchain/withdraw_types.cpp
Resolve #876

Not 100% sure what the problem here was... >= for asset ID mismatch is
defined to be false, but for some reason it was returning true. Anyways,
the logic is more explicit now. One can now cancel a bid in a user-
Cherry-picked ddbb48fd5eee4eb2a6504ac84797984ebe9dcf66

Get more desperate about paying fees in transaction builder;
resolves #876

Conflicts:
	libraries/wallet/transaction_builder.cpp
Properly register local accounts with different owner and active keys
Cherry-picked c584420b4889a0b0dda477a07458f9bb94f21e58

Improve checking and error handling for child account registration;
resolves #1101

Conflicts:
	libraries/wallet/wallet.cpp
Cherry-picked 597d74c99e2888e35b54f037dca1e4abe69ae040

Fix wallet_account_rename; resolves #1070

Conflicts:
	libraries/wallet/include/bts/wallet/wallet_db.hpp
	libraries/wallet/wallet.cpp
Partial cherry-pick of 6632ea0cc3811336ab400246f410cec42d47049f to fix compile

Allow parent accounts to sign some operations on behalf of the child

Conflicts:
	libraries/blockchain/account_operations.cpp
	libraries/blockchain/chain_interface.cpp
	libraries/blockchain/feed_operations.cpp
	libraries/blockchain/include/bts/blockchain/chain_interface.hpp
	libraries/wallet/wallet.cpp
	programs/web_wallet
Disabled unused wallet upgrade code