Embedded GPLv2 license.
fix spelling error.
add logtrace component

Logtrace is a component that could output the log into either a device
or a file. It has the ability to filter the log messages according to a
pre-module level. Define RT_USING_LOGTRACE in rtconfig.h if you want to
have a try.
Merge pull request #113 from grissiom/logtrace

add logtrace component
Embedded GPLv2 license in dfs
Embedded GPLv2 license in pthreads
Embedded GPLv2 license in components