TogglePin was incorrectly using the PINx pin for toggling, causing the
current pins (in addition to the requested ones) to be toggled, causing
stepping havoc.
Make ReadPin return the last value set by WritePin for proper testing.
Add a slow-path to TogglePin that goes through a read-write cycle. This
is useful both for testing and for platforms that don't have an
efficient toggle like AVR.
The cast to Level is incorrect, since the expression returns either 0 or
a positive value if the pin is set. The value is directly assigned to
the underlying uint8_t, meaning that Level::high won't match for levels
greater than 0.
Return a boolean and cast that to Level instead.
Remove the constructor from GPIO_pin so that we can use brace
initialization at compile time.
Rewrite the contents of pins.h to construct GPIO_pin types directly by
the use of a simple preprocessor macro.
Makes the code type-check and easier to read/extend.