Characters must be written atomically to the console

[Jiri Svoboda]

Currently the handler of VFS_WRITE in console expects that the provided data buffer consist of entire characters. If it does not, the incomplete characters won't be printed correctly.

This might not be the best behavior, because it means that anyone writing to the console file interface needs to know they are writing text (as opposed to binary data).

Currently 'cat' command in Bdsh is probably suffering from this.