make: Add target to show if boards that are supported by apps
[SQUASH ME] make: move info-boards-supported to Makefile.buildtests
make: Add info prefix for non-building targets in Makefile.buildtests
[SQUASH ME] make: Add info prefix for non-building targets in Makefile.buildtests
[SQUASH ME] Fix some error + simplify some calls
pyterm: adds timer function

/timer <interval> <command> now allows to schedule arbitrary commands to
be send to the node after the specified interval (in seconds).
Merge pull request #1569 from OlegHahm/pyterm_timer

pyterm: adds timer function
make: Make BOARDS a global macro for buildtests
[SQUASH ME] make: info-boards-supported is just
make: Add supported boards to info-build target
[SQUASH ME] make: remove debugging lines
[SQUASH ME] make: Move buildtest related PHONY targets to Makefile.buildtests
Merge pull request #1557 from authmillenon/make-list-show

make: Add target to show if boards that are supported by apps
native: remove redeclarations of sched_active_thread
Merge pull request #1574 from Kijewski/native-sched_active_thread

native: remove redeclarations of sched_active_thread
core: introduce KERNEL_PID_FIRST and KERNEL_PID_LAST
all over the place: use sched_active_pid
core: remove PID check duplication
core: let valid PIDs start with 1