Use customized command string in scons
link with libm.so

This fix the compiling error:

    /usr/lib64/gcc/x86_64-slackware-linux/4.7.2/../../../../x86_64-slackware-linux/bin/ld: build/components/rtgui/common/dc.o: undefined reference to symbol 'sin@@GLIBC_2.2.5'
    /usr/lib64/gcc/x86_64-slackware-linux/4.7.2/../../../../x86_64-slackware-linux/bin/ld: note: 'sin@@GLIBC_2.2.5' is defined in DSO /lib64/libm.so.6 so try adding it to the linker command line
    /lib64/libm.so.6: could not read symbols: Invalid operation
    collect2: error: ld returned 1 exit status
rtgui_demo: port to new API
simulator: no need to dump the bin file
create disk/{ad, nor, nand in bsp/simulator
enabe dfs_win32 in simulator when built on windows
Rename `--default-comstr` to `--verbose`
sync with rtgui-0.6
Merge pull request #22 from grissiom/rtgui-0.6

sync with rtgui-0.6
Merge branch 'simdev'
Merge pull request #17 from rogerz/master

Customize command string in scons
Add detail build result
Use build matrix
add all arm bsp to build matrix
Remove unsupported BSP
Fix build error in efm32
Merge pull request #24 from rogerz/auto-ci

Add all arm bsp to building matrix
Merge pull request #25 from rogerz/build-error

Fix build error in efm32
rewrite serial/uart code in simulator to support multi-uarts
fix bug in simulator/drivers/serial.c which deadlock may happen if multi-uart both output use printf