[horde] lightning set the calendar in read mode

[Gerard Breiner]

Hello,

I set up lightning to reload each of 2 mn for testing. I created a new 
event and published succesfully on my webmail. After 2 mn lightning 
warned me with this error : ICS_FILE and set up my calendar in read mod.
I suppose this is a well-known error but after searching on the net I 
didn't find anything.
May you help me please ?

Thanks by advance

Gerard