* travis: move build flags tests outside of hardware header

* mqtt: fix typo

* travis: use files instead of bundling test cases into script

* fixup! travis: use files instead of bundling test cases into script

* fix variable expansion, remove custom h at the end

* add ade7953 to sensors list

* custom.h path as variable

* shellcheck

* fix printf syntax, silent again

* fix bash 4.3 treating empty array as unset variable

* enable multiple Digital, Events & PulseMeter

* delete SPI dependency

* back to only one PulseMeter

* deprecared pins

* fix webui regexp and input length limits
* explain requirements in webui and headers

Isolated dependencies

sensors dependencies

enums, macros and prototypes.

I2C dependencies moved to actual sensor files.

definitelly redefine