improve test_hwtimer usefulness

make the delays noticeable for humans
use HWTIMER_TICKS macro for platform independency
substitute folder with directory
Merge pull request #544 from LudwigOrtmann/folder2directory

substitute folder with directory
increase inter-timer delay
Merge pull request #546 from LudwigOrtmann/test_hwtimer

improve test_hwtimer usefulness
fix callback offset
improve debug messages
fix overdue mitigation
use mutex in vtimer_sleep

this change prevents a race condition in case of
short sleep time

Fixes: https://github.com/RIOT-OS/RIOT/issues/550
ccnl: dynamic memory - appserver module
ccnl: dynamic memory - control module
ccnl: dynamic memory - client module
added the missing define for radio_packet_length_t on econotag
Merge pull request #509 from mehlis/ccn-lite-follow-up-6

Ccn lite follow up 6: try to save as much static memory as possible
improve error messages when tap ioctls fail
change wording

addresses https://github.com/RIOT-OS/RIOT/pull/555#discussion_r9118361
Merge pull request #555 from LudwigOrtmann/tap_error

improve error messages when tap ioctls fail
Fix errors in at86RF231 driver
Uncircumvent radio chip's status for IEEE 802.15.4 hardware

Currently the cc2420 and at86rf231 hardware addresses (IEEE 802.15.4
short and long) and frequency channel are read only from a global
variable in the driver.  This global variable is only set when the
user sets the address/channel though both parameters might be preset
by the hardware. This change lets the driver read this parameters
directly from the hardware.
math.h: remove unneeded math.h includes