Added means to document (temporarily) removed features. The file
contains a list of all modules/features that were removed for
various reasons (typically: not maintained anymore), so that these
can be reintegrated in a later point of time.

cpu: doxygen cleanup

mrf24j40: rewrite binary constants to hex

cpu/stm32_common: fix PLLs enabling and usage

core: thread_flags: Set sched_status_switch_request after waking a waiting thread

cpu/stm32f[0|1|3] unify stmclk with stm32_common

cpu/atmega_common: add i2c periph driver

drivers/dht: remove useless auto_init declaration

drivers, lps331ap: fix overshift error on 8Bit MCUs

boards/cpu: removed support for weio and lpc11u34

drivers: several fixes for drivers using I2C on 8Bit MCUs

    - bmp180: fix overshift error
    - hih6130: fix overflow in sleep interval
    - pn532: fix overshift error
    - bh1750fvi: fix overshift error
    - mpu9050: fix overflow error

cpu/sam0_common: fixed UART for samd21

sys: random: make use of submodules in Makefile

core: thread_flags: improve documentation

sc_vfs: add write command

core/msg: Set THREAD_FLAG_MSG_WAITING when queueing messages

Add driver for MY9221 LED controller and (based on that) the Seeed Studio Grove LED bar