core/state: always commit in batches, just finish if not needed later

core: fix invalid state reuse in chain maker based tests

common: Fix HomeDir detection

I am working on porting geth to [Ubuntu Core](https://developer.ubuntu.com/en/snappy/https://developer.ubuntu.com/en/snappy/). I am testing geth on a Raspberry PI and for Ubuntu Core the $HOME directory is unique for each application. See [here](https://developer.ubuntu.com/en/snappy/guides/filesystem-layout) for more information of their filesystem layout.

For some reason in Go `usr.HomeDir` returns a different value than `$HOME` in Ubuntu Core.

Adding this at the end of `HomeDir()`
```go
fmt.Printf("at HomeDir, user.HomeDir = %s and $HOME is %s\n", usr.HomeDir, os.Getenv("HOME"))
```

gives the following output

```
at HomeDir, user.HomeDir = /home/ubuntu and $HOME is /home/ubuntu/apps/geth.sideload/IJcODREBYbHO
```

With this commit, I propose giving precedence to the `$HOME` environment variable as is also suggested by the [homedir](https://github.com/mitchellh/go-homedir/blob/master/homedir.go) project.

core, eth/downloader: ensure state presence in ancestor lookup

core: transaction invalidation and reorganization fixes

eth/downloader: throttling tests are time-sensitive, don't run parallel

common: remove old RLP implementation, Value and ExtPackage

console crash on nil ptr

console: bugfix that causes the console to crash when connection to an endpoint without the personal api enabled

Light state

In order to make this happen, kill all remaining trivial uses of
common/{rlp,value}.go. The non-trivial ones have been updated earlier.

The test chain generated by makeChainFork included invalid uncle
headers, crashing the generator during the state commit.

The headers were invalid because they used the iteration counter as the
block number, even though makeChainFork uses a block with number > 0 as
the parent. Fix this by introducing BlockGen.Number, which allows
accessing the actual number of the block being generated.

p2p: resolve incomplete dial targets

The test expected the timeout to fire after a matcher for the response
was added, but the timeout is random and fired sooner sometimes.

This change makes it possible to add peers without providing their IP
address. The endpoint of the target node is resolved using the discovery
protocol.

This change simplifies the dial scheduling logic because it
no longer needs to track whether the discovery table has been
bootstrapped.

core: tx pool skip price validation for "owned" transactions

eth: fix #2076, where end of hash query was interpreted number query

rpc: optionally passing context argument to rpc v2 api methods

core, eth, node, rpc: port the admin and debug API

Makefile, cmd/geth: support building Android archives

rpc: new RPC implementation with pub/sub support

crypto: "Crypto" -> "crypto" in web3 key format

Makefile, cmd/geth: assemble ios xcode frameworks