Removed the legalese confirmation dialog. This closes #1992

* xeth, rpc: implement eth_getNatSpec for tx confirmations
* rename silly docserver -> httpclient
* eth/backend: httpclient now accessible via eth.Ethereum init-d via config.DocRoot
* cmd: introduce separate CLI flag for DocRoot (defaults to homedir)
* common/path: delete unused assetpath func, separate HomeDir func

* lines with leading space are ommitted from history
* exit processed even with whitespace around
* all whitespace lines (not only empty ones) are ignored

add 7 missing commands to admin api autocomplete

registrar: methods now return proper error if reg addresses are not set. fixes #1457

rpc/console: fix personal.newAccount() regression. Now all comms accept interactive password

registrar: add registrar tests for errors

crypto: catch AES decryption error on presale wallet import + fix error msg format. fixes #1580

CLI: improve error message when starting a second instance of geth. fixes #1564

cli/accounts: unlock multiple accounts. fixes #1785
* make unlocking multiple accounts work with inline <() fd
* passwdfile now correctly read only once
* improve logs
* fix CLI help text for unlocking

fix regression with docRoot / admin API
* docRoot/jspath passed to rpc/api ParseApis, which passes onto adminApi
* docRoot field for JS console in order to pass when RPC is (re)started
* improve flag desc for jspath

common/docserver: catch http errors from response

fix rpc/api tests

common/natspec: fix end to end test (skipped because takes 8s)

registrar: fix major regression:
* deploy registrars on frontier
* register HashsReg and UrlHint in GlobalRegistrar.
* set all 3 contract addresses in code
* zero out addresses first in tests

* Renamed ChainManager to BlockChain
* Checkpointing is no longer required and never really properly worked
when the state was corrupted.

The test genesis block was not written properly, block insertion failed
immediately.

While here, fix the panic when shutting down "geth blocktest" with
Ctrl+C. The signal handler is now installed automatically, causing
ethereum.Stop to crash because everything is already stopped.

Added a `Difference` method to `types.Transactions` which sets the
receiver to the difference of a to b (NOTE: not a **and** b).

Transaction pool subscribes to RemovedTransactionEvent adding back to
those potential missing from the chain.

When a chain re-org occurs remove any transactions that were removed
from the canonical chain during the re-org as well as the receipts that
were generated in the process.

Closes #1746

Changed the version number of geth to 1.2.0 so that dev builds are now properly build (instead of master). Note to self; increase version number to 1.2.1 for our next actual release.

Dev mode enabled some debugging flags such as:

* VM debugging mode
* Simpler proof of work
* Whisper enabled by default
* Datadir to a tmp datadir
* Maxpeers set to 0
* Gas price of 0
* Random listen port