A templated hal::Handle class is used to wrap handles to make them move-only.
This eliminates a lot of boilerplate move constructor/assignment code
in the main WPILib classes. HAL_SPIPort and HAL_I2CPort are also wrapped.
The wrapper class does not implement destruction. This would require the
wrapper class to be handle-specific (rather than generic) and would result
in more code added than it removed, plus would add header dependencies on
more HAL headers. In addition, some HAL handle release functions are more
complex (e.g. have return values) and can't be easily mapped to a destructor.
This allows HAL_CloseI2C() and HAL_CloseSPI() to be noops, which makes
enabling move semantics in the I2C and SPI wpilibc classes easier and
cleaner.
Fixes#1328.
The old headers were moved into folders because doing so avoids polluting
the system include directories.
Folder names were also normalized to lowercase.
