This fix addresses an issue with filters that were (possibly) not yet
added to the filter queues but were expected. I've added additional nil
checks making sure it doesn't crash and swapped the installation of the
filter around so it's installed before use.

Closes #1665

makefile: built in cross compilation targets

core, xeth: chain reorg move missing transactions to transaction pool

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.

core: separate and contain POW verifier, extensive tests

tests: update common test wrappers and test files

core: transaction nonce recovery

When the transaction state recovery kicked in it assigned the last
(incorrect) nonce to the pending state which caused transactions with
the same nonce to occur.

Added test for nonce recovery

core: allow modifying test-chain block times

common: Update README.md for the current package name

cmd/geth: extradata is correcly initialized with console

timer bugfix when clearInterval was called from within the callback

core, eth, miner: use pure header validation

all: move common.Database to ethdb and add NewBatch

eth, rpc: standardize the chain sync progress counters

adds extradata flag

new solc api - late fixes

* use legacy version matcher
* optimise just a boolean flag
* skipf for messages in tests

Storing a value in LevelDB copies the bytes, modifying the value
afterwards does not affect the content of the database. This commit
ensures that MemDatabase satisfies the same property.

common/compiler: new solc API

rpc/comms: fix #1795, ensure IPC path exists before binding

Change go-uuid to use the current supported repository.

* adapt to new compiler versioning
* use compiler version as language version
* implement new solc API for versions >= 0.1.[2-9][0-9]* fixes #1770
* add optimize=1 to options
* backward compatibility (for now) for <= 0.1.1, and old versions (0.[2-9][0-9]*.[0-9]+)
* introduce compilerOptions to ContractInfo
* clean up flair, include full version string to version line and ContractInfo