Merge pull request #286 from aozima/pulls

Pulls
device: only increase the ref_count when device is truly opened
shell: print the ref count in `list_device`
Merge pull request #287 from grissiom/device-fix

Device fix
[LwIP] Fix the MEMP_NUM_TCP_SEG issue.
[lwIP] code cleanup
[libc] code cleanup.
[Finsh] Enhance mv command.
Merge branch 'master' of https://github.com/RT-Thread/rt-thread
[DFS] Add dfs_filesystem_get_mounted_path() function.
Add WEAK definition; Add AUTO Refresh option for block device.
Add WEAK definition;
[lwIP] Add LWIP_NO_RX_THREAD/LWIP_NO_TX_THREAD options for lwIP.
[BSP] Fix compiling error
bsp: add zynq7000
Merge pull request #288 from grissiom/zynq-7000

bsp: add zynq7000
[lwIP] Fix the usage issue of NETIF_LINK_CALLBACK.
add Freescale k64F bsp. FRDM-K64 based
change the uart name
rename frdm-k64f