When interrupts are cancelled on any interruptable class, the resource is now
freed. Previously, the resource was only freed if the object is destructed
before CancelInterrupts() is called, so it was impossible to create and
destruct more than 8 interrupts.
The interrupts resource object is now in InterruptableSensorBase instead of
SensorBase.
A synchronous interrupt integration test was added.
Change-Id: I0806176340cecd4c1480dd8f043474cc05919f24
Analog interrupts now work in C++.
The interrupts Resource was moved from a global in DigitalInput
to a static member of SensorBase.
An analog interrupt IT was added, and the digital interrupt one modified
to prevent a linker error.
Change-Id: I9a300daafed15e9666a4ccb405a509615e3dbb06
