Added POV image effect

Setup is really easy, after first boot and WiFi/LEDs setup:
go to wled.local/edit and upload a couple image to WLed's filesystem.
Only PNG is supported right now, further support for GIF is planned.
The image should be as wide as the 1D segment you want to apply to.

When done, go to the Effect page on the UI, select "POV Image" effect.

You could also update the image with a post to the JSON-API like this:
curl -X POST http://[wled]/json/state -d '{"seg":{"id":0,"fx":114,"f":"/axel.png"}}'

The segment should move at around 120RPM (that's 2revolutions per seconds) for an image to showup.
More informations and pictures here : https://lumina.toys

platformio_override.sample.ini

@@ -29,6 +29,8 @@ lib_deps = ${esp8266.lib_deps}
 ;  ;gmag11/QuickESPNow @ ~0.7.0 # will also load QuickDebug
 ;  https://github.com/blazoncek/QuickESPNow.git#optional-debug  ;; exludes debug library
 ;  ${esp32.AR_lib_deps} ;; used for USERMOD_AUDIOREACTIVE
+;  bitbank2/PNGdec@^1.0.1 ;; used for POV display uncomment following
+
 build_unflags = ${common.build_unflags}
 build_flags = ${common.build_flags} ${esp8266.build_flags}
 ;
@@ -152,6 +154,8 @@ build_flags = ${common.build_flags} ${esp8266.build_flags}
 ;   -D TACHO_PIN=33
 ;   -D PWM_PIN=32
 ;
+;  Use POV Display usermod
+;   -D USERMOD_POV_DISPLAY
 ; Use built-in or custom LED as a status indicator (assumes LED is connected to GPIO16)
 ;   -D STATUSLED=16
 ;