this time without the amazingly silly bug

Otherwise, get_field() will return NaNs after once every few calls to
read() during compassmot on PX4 platforms, which causes compassmot to fail.

This is a quick hack around the deeper issue, which could be something
like the PX4 mag driver experiencing starvation and skipping mag reports,
buffer overrun or something else that causes mag reports to be dropped.
Or perhaps we should never expect in the first place that we will always
receive at least one mag report between calls to read().

Values from 0 ~ 100 control amount of filtering on roll and pitch input.
100 = no filter so crisp feel, 0 = a lot of filtering so very sluggish
response

including raw temperature and pressure values

The real purpose of this small change is to kick off the autobuilder for
the AC3.1.1 release.