Instead of just doing a static cast to the desired class, use a method
named "from". Pros:
- When we have data shared on the parent class, the code is cleaner in
child class when it needs to access this data. Almost all the data
we use in AP_HAL benefits from this
- There's a minimal type checking because now we are using a method
that can only receive the type of the parent class
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.