Fix an issue with initialization of channels that on-line changed their function.
For the curious people that the code size overhead of having any aux channel do any function (with this code) is 44 bytes.
To see wich code I'm talking about, do a git diff 05057ac2d455..this_commit (replace this commit with the commit hash of this commit)
This simplifies code sharing between ArduCopter and Arduplane at the expense of 48bytes.
Moved CH_x defines out of the defines.h file and into the library where they belong
Amilcar Lucas