remove .cpp from the resulting suffix, since .ipp already implies it is c++
update comments once again

fixes #2479

- remove 'local' index and replace sensor code depending on it with the
  existing 'slot' aka 'magnitude index' used in value() and type()
- common method to store and retrieve ratios for voltage, current,
  active power and energy. default implementation is no-op, sensor
  should implement ratio adjustment & calculations to use 'slot' indexes
- re-implement 'expected' values ui. display the actual ratio values,
  and have a separate page for updating them in a more apparent way
- remove legacy settings that were adjusting expected values
- remove legacy settings that were resetting ratios and analog calibration
- generic webui action caller, add ratios and analog calibration resets

all of 'emon' sensors were updated to utilize the new approach to the
ratio handling. pulsemeter is somewhat an outlier, but it is unclear
whether removing the energy ratio is justified

terminal part was also updated
- implement `expected` command that hooks into the new ratioFromValue
  (and what webui uses to calculate ratios)
- implement `energy` command to list only MAGNITUDE_ENERGY
- remove old pzem004t commands doing ratio reset and total energy count

another global update is related to espurna::duration
- rework module-local heartbeat and led durations into a global
  espurna::duration
- update sensor internals to use specific units instead of multiplying things
  on line-by-line basis. export count() to the api

Implement strongly-typed time units via std::chrono,
compile-time checks with static delays and limit possible values in the
pattern parser. Clamp 'repeats' as well, instead of relying on overflow

Rework internal loop & template runners, so there's no need to
proxy status and led struct all over. Instead, simply declare two
separate funcs that are supposed to be run during the pattern and at
it's end.

Instead of cloning the 'delays' array, implement a sequence iterator
that is tracking the currently used delay and it's repeats, and which
also jumps to the next entry in the list.
(but, this uses c++ iterators, and *may* be prone to errors)

Implement small terminal command 'led <ID> [<PATTERN STRING>]'.
Running without the 'PATTERN STRING' resets the LED to the values in settings.

Move re2c-generated parser back into a separate file, use .cpp.inc as
include and .re as the source

ref. #2476, fix 'finite' pattern handling