update CMSIS version to 3.20
Add sector size check when mounting a FAT file system.
Include rtconfig.h file in rtdebug.h file.
Merge pull request #235 from aozima/pulls

update CMSIS version to 3.20
[DFS] fix the wrong field comparison in FAT mount.
[DFS] Fix file size issue

This issue causes fstat & lseek not correct.
[Finsh] Add ifconfig command implementation.
Add directory and SConscript for Espruino.
Add more feature on buildlib
simulator: fix exit issue when close RTGUI window
dfs: support copy directory
Merge pull request #237 from prife/dfs

dfs: support copy directory