    4. if a file is missing in a consecutive order, you may get a glitch in the sound 
    5. As the Adafruit Music Maker Shield library does not support to jump to a specific 
       position within a file, the box can always only start from the beginning of a track.
-
-   While the album (or file) is played an operations light is fading up and down in intensity. 
-   
-   On warnings or errors a warning or error light is lit up respectively. There are 3 different  
-   warning or error conditions:
+   
+   
+   Warnings and errors
+   ---------------------------------------------------------------------------------------
+   On warnings or errors a warning or error light is lit up respectively. There are 3 
+   different warning or error conditions:
    1) Missing information for playback warning
    2) Low Battery warning
    2) Missing hardware error
    
-   Errors shown via the error light (also cause the system to halt and the arduino must be turned off):
+   Errors shown via the error light (also cause the system to halt):
    - Music Maker Shield not found
    - Music Maker shield not on an interrupt enabled pin
    - SD card not found
    - NFC Reader not found
 
    Warnings shown via a light (Arduino can stay turned on):
-   - Low battery warning (surely the arduino will turn off but until then it will continue to operate)
+   - Low battery warning (surely the arduino will turn off but until then it will operate)
    - no directory found for the NFC Tag (aka TrackDB is missing an entry for the Tag)
    - no directory found on the SD card that match the NFC Tag TrackDB record
    - no files in the provided directory

   - Next Track           - play the next track in a consecurtive list of ordered files
   - Pause / Resume       - pauses the playback or unpauses a paused playback
   - Light on / off       - turn the operations light fader on or off


   Some features (as e.g. Remote Control, Buttons or operation LED etc.) can be turned off 
   or on via #define switches in the code below.
   
   Used Pins:
     NAME             PIN  USAGE
   - CLK / PN532_SCK   13  SPI Clock shared with VS1053, SD card and NFC breakout board 
   - MISO / PN532_MISO 12  Input data from VS1053, SD card and NFC breakout board 

   This line connects the Tag UID with the aformentioned directory plus the number of the track
   with which to start playback:
   
      46722634231761290   the UID of the NFC Tag
      findorie            the directory from which to play the files
      1                   the number of the track with which to start playback - here the 1st 

   To use this implementation you need to activate the configuration   NFCTRACKDB   
   You will also need to create the necessary TrackDb files. This can be done with the program
   createTrackDb.ino from this repository.
   
   
   Playback and controls
   ---------------------------------------------------------------------------------------
   Regardless of the way the program retrieved the information on which directory to play 
   (NDEF message or TrackDB), it will store this in the global var plrCurrentFolder and then 
   start a for-loop beginning with the provided first track until all consecutive numbered 
   tracks are played - for this it counts the number of files in the given dierctory. 
   
   While the album (or file) is played an operations light is fading up and down in intensity. 
   
   After playback of all files is finished, the program will resume it's main loop, delay 
   operation for roughly 15 seconds (to give the user the chance to remove the just used Tag 
   from the reader) and then wait until it detects the next tag.
   
   While advancing through the files in the directory, the program will update the TrackDB-File 
   with  the number of the currently played track. Doing so allows for interrupted playbacks - 
   tag is removed and later put back on when the playback will start with the last track in 
   playback. 
   
   
   Restrictions
   ---------------------------------------------------------------------------------------
   For this to work, a couple of restrictions are in place:
   1. All filenames must be in the format  trackXXX.mp3, where XXX is a numbering from 001 to 127
   2. Follows from 1: You can have a maximum of 127 files per directory. I use a char to count the
