Adds a close function pointer template parameter to hal::Handle. This allows default destructors in many places.
The status parameter has been removed from close functions; in most places it was not used. Where it was, an error is printed instead.
The FPGA API takes microseconds directly, instead of a scaled value. Also add a new HAL level API to trigger multiple DIOs with the same pulse at once.
The old headers were moved into folders because doing so avoids polluting
the system include directories.
Folder names were also normalized to lowercase.
