Merge pull request RT-Thread#425 from BernardXiong/master

[DeviceDrivers] Add more sensor drivers.

Merge pull request RT-Thread#370 from grissiom/romfs-next

romfs: fix a use-before-set bug on checking the dirent

[LIBC] fix the open mode when using fopen in arm libc.

RT-Thread v2.0.0 beta

RT-Thread v1.2.2 release

RT-Thread v2.0.0 alpha

RT-Thread v1.2.1 release.

RT-Thread 1.2.0