Move attribute definitions all into AP_Common, rather than being split between two files
Remove unused SITL_printf macros
Stop AP_Common including board information
Include AP_Common.h in AP_HAL::Sempahore for WARN_IF_UNUSED; this was the cause of a circular import problem fixed by other commits in this patch.
This commit changes the way libraries headers are included in source files:
- If the header is in the same directory the source belongs to, so the
notation '#include ""' is used with the path relative to the directory
containing the source.
- If the header is outside the directory containing the source, then we use
the notation '#include <>' with the path relative to libraries folder.
Some of the advantages of such approach:
- Only one search path for libraries headers.
- OSs like Windows may have a better lookup time.