cstimer interface replaced with os_timer, which is 30..50% faster

...g/efm32gg332f1024_wandstem/interfaces-impl/cstimer_impl.h

...2gg/efm32gg332f1024_wandstem/interfaces-impl/os_timer.cpp

...arch/cortexM4_stm32f4/common/interfaces-impl/os_timer.cpp

...h/cortexM4_stm32f4/common/interfaces-impl/portability.cpp

...m32f407vg_stm32f4discovery/interfaces-impl/deep_sleep.cpp

miosix/config/Makefile.inc

miosix/interfaces/os_timer.h

miosix/kernel/kernel.cpp

miosix/kernel/scheduler/control/control_scheduler.cpp

miosix/kernel/scheduler/edf/edf_scheduler.cpp

miosix/kernel/scheduler/priority/priority_scheduler.cpp

miosix/kernel/stage_2_boot.cpp

miosix/kernel/timeconversion.cpp

miosix/kernel/timeconversion.h

miosix/stdlib_integration/libc_integration.cpp