kernel: move CONFIG_SMALLEST_FPAGE_SIZE back to implementation
mk: migrate to Kconfig completely

Configuration file include/config.h is now deprecated.
Documentation: improve syntax
mk: reduce image size by eliminating hidden functions

The whole hidden functions can be garbage collected if unused locally,
and here is the comparison about image size:

[before]
  f9.bin: 59672 bytes
[after]
  f9.bin: 59092 bytes

Toolchain options:
  -ffunction-sections,
  -Wl,--gcsections,
Implement tickless
Implement tickless verification
Change tickless verify range, from event create to event trigger
enable ktimer tickless by default
kernel: conditional build of tickless scheduling
Modify tickless verification display
Fix tickless does not recover heart beat
Fix call tickless_verify_stop before start
mk: migrate to Kconfig for tickless
conditional build of tickless scheduling status tracker
irq: use PendSV to avoid disabling irq in context-switch
Move platform dependent codes from tickless_verify to hwtimer

Signed-off-by: Jim Huang <jserv@0xlab.org>
kernel: fix build failure because of tickless
Merge branch 'test-tickless'

Fixes #19
add southernbear in author list
Close IRQ in context switch to avoid abnormal sampling result

This abnormal sampling results from context switch processing in PendSV
being preempted by ktimer IRQ which triggers sampling event periodically.

Fixes #40

Signed-off-by: Jim Huang <jserv@0xlab.org>