scheudler: Do not include irq load in thread load
scheduler: Fix power saving mode and other minor improvements
cpufreq: Rank modules and choose the best one
scheduler: Clean scheduler_common.h

scheduler_common.h is now meant for types, variables and functions used
by both core scheduler code and implementations of scheduler modes.
Functions like switch_thread() and update_thread_times() do not belong
there anymore.
kernel: Make CACHE_LINE_ALIGN visible in the whole kernel