tests: add test_vtimer_msg_diff

This test sets three timers and renews them periodically, showing the
difference they accumulate.
tests: test_vtimer_msg_diff: use array for timers, change first to 1s
tests: test_vtimer_msg_diff: add some timers, change max values
tests: test_vtimer_msg_diff: Makefile s/PROJECT/APPLICATION/g
tests: test_bloom: fix PROJDEPS concurrency

Our buildtests build one project concurrently for multiple boards.
The current creation of the `PROJDEPS` for `test_bloom` might fail if

* board `A` notices that the dependency is missing and gets preempted,
* board `B` creates the dependency and gets preempted,
* board `A` starts the creation but gets preempted in the middle of the process,
* board `B` works with a half complete created file.

This PR creates the dependency in the individual `BINDIR`.
make: s/PROJDEPS/APPDEPS/

fixes https://github.com/RIOT-OS/RIOT/issues/1284
doc: improve APPDEPS example

Addresses https://github.com/RIOT-OS/RIOT/pull/1339#discussion_r14050325
make: evaluate the Git SHA only once
cpu: added low-level pwm driver impl for lpc2387
boards: added periph_conf.h for msba2 and avsextrem
drivers: some adjustments to low-level pwm driver

- adjusted doxygen and boilerplate
- changed return values for start and stop functions
board - pttu: added periph_conf.h
sys: added color module
cc110x_ng: build cc110x_spi for all boards except chronos
you can never have enough debugging in RPL
some minor fixes and debugging
set correct transceiver stack size for debugging
fixed debugging for cc110x
net: IPv6: RPL: more debug output
rpl: debug: use DEBUGF where necessary