It's possible to use the internal clock in PCA96895 if we account for
the drift it contains. This is a bit different from solutions in other
projects like the Adafruit library and the PX4 firmware: instead of
applying a correction to the final frequency we apply the correction to
the clock since this is the source of the error.
With this fix we arrived to much better results across different lots of
sensors.
The Navio board continues to use the external clock and should have no
difference behavior.
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.
