Fixed the bug where period bounds weren't being updated according to the sample_resolution parameter. Also artificially limited the period resolution to 1ms
Enabling single pulse mode now changes the status screen on the LCD display. Single pulse mode also no longer uses interrupts, and instead uses HEAVILY debounced inputs for enable, arm, and fire.
Updated single pulse mode so that it has an ENABLED, ARMED, and FIRED state. The enabled pin toggles the single fire mode. The armed state toggles whether it's armed or not. The fire pin will only fire if it has been armed.