Restructure files for simpler relation between files

Remove double definitions by removing file specific header files.
Rename files to remove the spacemouse prefix. Change includes according
to these changes. Change objects list in Makefile accordingly.
Change header guard name according to filename
Merge branch 'feature/restructure' into develop
remove double errno.h include
Use macros to make get_led() more portable and easier to read
Add _device_get_max_axis_deviation() with fallback support for EV_REL

Function returns the maximum deviation, both on postive and negative
axes, and makes sure that this value is the same for all axes.

Uses a fallback value of 500 for EV_REL.