Improved consistency and formal correctness of all existing .equals methods to meet IntelliJ's convention.

* added null handling so equals methods return false for null argument
* replaced instanceof with getClass to force strict type equality
* added @Override for equals and hashCode where missing
* minor refactorings in equals methods to simplify and improve consistency
* added missing hashCode for ListMessage based on equals definition

Things that HAVE NOT changed:

* set of attributes used for equality checking
* hashCode calculation (except for added hashCode in ListMessage)
* correlation between equals and hashCode
* no new equals methods added
Fixed type references in javadoc to avoid IntelliJ error reports on rebuild.
Dealt with several compiler notices by verifying and then fixing or suppressing. Reduces compilation output noise.
Renamed proofOfWorkLimit to maxTarget along with get/set and minor refactorings.

* proofOfWorkLimit renamed to maxTarget to get it more inline with commonly used terminology (wiki, etc.)
* some misleading local variables renamed from 'difficulty' to 'target'
Implement ScriptChunk.toString() by extracting relevant parts from Script.toString().
Implement standard checks for BIP62 shortest possible data push rules. Also fix ScriptBuilder so it doesn't build longer than necessary data pushes any more.
Add qertoip to AUTHORS
renaming to nonexisting file on Windows

The method fails in case the file does not exists before renaming. canonical.delete() returns false in that case and the method throws an exception.
Teach TransactionOutput.toString() to print send-to-pubkey and send-to-multisig types.
Payment channels: update example client to reflect API changes.
Convenience ScriptBuilder.addChunk() method can add arbitrary script chunks.
Fix 'shortest possible pushdata' logic for transaction inputs. Also add a testcase.
Bloom bugfix: track false positives in blocks including when the tx was broadcast within the session, and don't print an error from the wallet in this case. Should have no impact beyond more accurate FP rate calculations.
Fix scrypt library hash.
Bloom: don't requery mempool if the filter is only being refreshed to force down FP rate.
Update note about regenerating protobuf bindings.
Save value of inputs when completing transactions and persist it to the wallet protobuf. Determine the fee of a transaction in case we have all the values.
HD wallets alpha preview
HD wallets: add a Wallet.getKeyChainSeed method.
WalletTool: allow creation of a wallet from a given [word] seed.