Remove IsFromMe() check in CTxMemPool::accept()

Fixes issue #2178 : attacker could penny-flood with invalid-signature
transactions to deduce which addresses belonged to your node.

I'm committing this early for code review; I still need to write up
a test plan.

Executive summary of fix: check all transactions received from the network
for penny-flood rate-limiting before adding to the memory pool. But do NOT
ratelimit transactions added to the memory pool:
  - because of blockchain reorgs
  - stored in the wallet and added at startup
  - sent from the GUI or one of the send* RPC commands (CWallet::CommitTransaction)

The limit-free-transactions code really should be a method on CNode, with
counters per-peer. But that is a bigger change for another day.
Add optional transaction index to databases

By specifying -txindex when initializing the database, a txid-to-diskpos
index is maintained in the blktree database. This database is used to
help answering getrawtransaction() RPC queries, when enabled.

Changing the -txindex value requires a -reindex; the client will abort
at startup if the database and the specified -txindex mismatch.
Let limitfreerelay=0 reject ALL free transactions
spendfrom.py sends coins from a particular address or addresses

Should be both useful and also a pretty good demonstration of
using the raw transactions API.
Merge pull request #2168 from sipa/txindex

Add optional transaction index to databases
full translations update

- fetch current translations from Transifex
- update bitcoinstrings.cpp and bitcoin_en.ts
Merge pull request #2213 from Diapolo/translations

full translations update
Check only 288 blocks at startup by default
Merge pull request #2222 from sipa/check288

Check only 288 blocks at startup by default
Merge pull request #2182 from gavinandresen/addressoracle

Remove IsFromMe() check in CTxMemPool::accept()
Treat non-final transactions as non-standard

At least one service that accepted zero-confirmation transactions
was vulnerable because an attacker could send a transaction
with a lock time far in the future, and then have plenty of time in
which to get a double-spend mined (perhaps from a miner who wasn't
on the network when the first transaction was broadcast).

That is a variation on the "Finney attack". We still don't
recommend anybody accept 0-confirmation transactions as final
payment for anything. This change keeps non-final transactions
from appearing in the wallet, and, assuming most of the network
accepts this change, will prevent them from being relayed until
they are final.
Merge pull request #2162 from gavinandresen/spendfrom

spendfrom.py sends coins from a particular address or addresses
Merge pull request #2223 from gavinandresen/nonfinalnonstandard

Treat non-final transactions as non-standard
Merge pull request #1549 from TheBlueMatt/addnoderpc

Addnode optimization and addnode access via RPC
Remove support for pre-checksum undo files
Rename database directories
New seed nodes, from http://bitcoin.sipa.be/seeds.txt
Merge pull request #2234 from gavinandresen/seednodes

New seed nodes, from http://bitcoin.sipa.be/seeds.txt
Merge pull request #2231 from sipa/cleanups

Two cleanups before 0.8
CValidationState framework