send tx relay flag with version
Remove broken option to skip input checking for wallet txn.

Conflicts:
	src/main.cpp
	src/main.h
	src/rpcrawtransaction.cpp
Refactor fee rules to make them actually readable.

This (nearly) doesn't change fee rules at all:
 * To make it into the fee transaction area, the dPriority comparison
   changed from < to <=
 * We now just ignore transactions > MAX_BLOCK_SIZE/4 instead of
   doing some calculations to require increasingly large fees as
   size increases.

Conflicts:
	src/main.cpp
	src/main.h
qt: allow user to choose data directory

This adds an introduction screen that is shown when the client is first
started in which the user can choose a data directory.

It is also possible to force the intro screen to appear using command
line argument `-choosedatadir`.

The user is warned that the client will download and store 10Gb of data.
The intro screen shows how much space is available on the device that
contains the chosen directory and warns if this is less than the 10Gb.

To make it possible to translate the introduction dialog, the initialization
sequence is changed so that translations are
loaded before the data directory. This has the by-effect that it is
no longer possible to specify a language in bitcoin.conf inside the data
directory.

Conflicts:
	src/qt/bitcoin.cpp
Progress update