* rpn: check status to avoid rescheduling

* keep existing op, add name hint

- general conversion from .ino modules into a separate .cpp files
- clean-up internal headers, place libraries into .h. guard .cpp with _SUPPORT flags 
- fix some instances of shared variables instead of public methods
- tweak build system to still build a single source file via os environment variable ESPURNA_BUILD_SINGLE_SOURCE

* support GPIO setting in WebUI
* experimental led pattern support
* support loading settings in setup() (not yet fully working)

* relay: compare sum of physical + dummy relays instead of just dummy

* typo

- mask is defined as (relay# status << number)
- transparently handle base-2 and base-10 numbers
- if the relay mode requires us to save the mask, it will be saved as base-2