Version 0.3.1

See README.md for currently supported functions.

Changed the way various structures are initialized. This is now a two step process. For example, the SPI structure should now be initialize via something like:

    var gpio : PiGPIO = .{};
    var an_spi_connection = gpio.spi();

The call to "spi" can be processed at comptime and does not require that the PiGPIO's connect call has been made.

Then to open the SPI interface:

    try gpio.connect( allocator, null, null );
    defer gpio.disconnect();

    try an_spi_connection.open( 0, 100_000, .{} );