Docs and improvements for timer

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>
Doc fix

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>
Update testcases

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>
Add missing file in Makefile.am

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>
Fix spin::intruse::list compile error

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>
Fix timer bug

Signed-off-by: LAN Xingcan <lanxingcan@gmail.com>