cpu: msp430: renamed msp430x16x to msp430fxyz
cpu: lpc2387: integrated lpc_common into lpc2387

Rationale 1: The common part made only sense for (some) NXP ARM7 MCUs,
but was misleading for MCUs like the LPC1768.

Rationale 2: The common part was only used by one specific MCU
implementation - no need to outsource it.
sys: rename lib to hash_string

That was the onyl remaining module in this folder.
tests/unittests: merge lib-ringbuffer into core

Fixup for https://github.com/RIOT-OS/RIOT/pull/2017
Merge pull request #2151 from OlegHahm/lib_hash_string

sys: rename lib to hash_string
Merge pull request #2118 from OlegHahm/simplify_cpu_folder_structure

cpu: simplify folder structure
doc: fix drivers/srf02 documentation
doc: fix drivers/srf08 documentation
Merge pull request #2160 from PeterKietzmann/fix_srf_ultrasonic_doxy_warnings

doc: doxygen fix srf02/srf08 ultrasonic warnings
Merge pull request #2157 from LudwigOrtmann/unittests-lib

tests/unittests: merge lib-ringbuffer into core
test/driver_nrf24l01p: changed default GPIOs

not all boards have GPIO_x > GPIO_7, so the new values are
safer to use.
Merge pull request #2161 from haukepetersen/fix_test_nrf24

test/driver_nrf24l01p: changed default GPIOs
vtimer: set custom msg_t.type with vtimer_set_msg

Currently, when using vtimer_set_msg the corresponding msg_t is filled
with the MSG_TIMER ("12345") type.
This approach makes it difficult to differentiate between incoming
messages via vtimer_set_msg.

In this PR I introduce another parameter for the vtimer_set_msg
function to specify a custom msg_t type.
Merge pull request #2162 from cgundogan/vtimer_set_msg_param_type

vtimer: set custom msg_t.type with vtimer_set_msg
trickle: separation of rpl and trickle
This PR introduces trickle as an independent module.
Currently, trickle is interleaved with rpl, which means that
trickle is not usable by other protocols than rpl.
Trickle's implementation would not work properly even for rpl if multiple dodags
were used, since it is only possible to initialize just one trickle
timer.

In this PR I introduce a `trickle_t` struct holding the state of one
trickle thread. Thus, it is possible to initialize several trickle
timers, each for one dodag or even for other protocols than rpl.
The function and the appropriate arguments to be executed by trickle
are passed in a generic way through an `trickle_callback_t` struct.

During the refactoring I was able to eliminate one of trickle's threads.
trickle: changed the trickle implementation to be a single thread,
handling multiple trickle counters via the message API.
I also added trickle to auto_init
rpl: merged routing table and dao thread into one
added missing pid assignment
rpl: RPL/Trickle with only *one* thread

This PR is *based* on my previous work in PR #1839
and proposes an approach to reduce the thread count of RPL.

The current RPL/Trickle stack needs about 5 threads to handle tasks
like updating the trickle timer, routing entries and the transmission of
DAOs.

This PR modifies RPL to use only one thread with a looped `msg_recv()` call.
The message is then multiplexed to the right task.
deleted unnecessary variables