Since wsn430-v1_3b and wsn430-v1_4 do have different radio configurations we need to separate `board.h` for them, so this moves their currently common `board.h` to `board_common.h` to be included by later introduced `board.h`
Since wsn430-v1_3b and wsn430-v1_4 do have different radio configurations we need to separate `board.h` for them, so this moves their currently common `board.h` to `board_common.h` to be included by later introduced `board.h`