Got rid of a few kB in the binary image by removing F-macro from numerous 1 or 2 character flash strings.
These very short strings take more space in flash and memory when using the F-macro.
Also appending to a string using a `'a'` character definition takes less resources compared to a one-character string `"a"`.
* initial support for TSL2591 sensor
* return lux, visible, ir and full light separately
* better plugin init
* check sensor initialization before reading it..
* incorporated a few pending fixes for the adafruit library
* minor typo
TD-er
Florin
krikkandDatuX