boards/chronos: clean up display driver a bit

reduce scope of variables
remove useless comments and spaces

saves 2 bytes =)
native: increase rtc realism

Prevent rtc enabling when not initialized.
 core: simplify mutex signatures
core: simplify mutex initializer
core: remove unneeded calls to mutex_init()
Merge pull request #1440 from Kijewski/issue-1436

core: simplify mutex signatures
doc: doxygen: EXTRACT_STATIC = YES
doc: little mutex.h fixes

- a university is not an author
- move internal tags to the right place
Merge pull request #1489 from LudwigOrtmann/minidoc

doc:   #1440 follow up
Merge pull request #1474 from LudwigOrtmann/chronos_cleanup_display

boards/chronos: clean up display driver a bit
Merge pull request #1477 from LudwigOrtmann/native_rtc_increase_realism

native: increase rtc realism
doc: fix most occurences of FU as an author

.. but only if there are other authors as well
Merge pull request #1490 from LudwigOrtmann/noauthor

doc: fix all occurences of FU as author
doc: some more author fixes

fix all occurences of INRIA as an author
correct Oliver Hahms authorship and indentation
Merge pull request #1491 from LudwigOrtmann/noauthor2

doc: some more author fixes
tests: Rename functionality tests to funct_…
Add expect script for funct_bitarithm_timings
Fix expect script of funct_hwtimer
Add expect script for funct_hwtimer_spin
[WIP] Add globally unified test target `make test`