UserEvent appears to corrupt event parsing

It appears that if a UserEvent is sent like this:

exten => _X.,1,UserEvent(EVENTHIS|billing=yes)

This is when Ragel gets confused. While on the other hand if you do something like:

exten => _X.,1,UserEvent(LOGVARIABLES|invoice:yes)

We then get the events in Adhearsion as follows:

INFO event_logger: Adhearsion::VoIP::Asterisk::Manager::ManagerInterfaceEvent: #<Adhearsion::VoIP::Asterisk::Manager::ManagerInterfaceEvent:0x175f110 @headers={"invoice"=>"yes", "Privilege"=>"user,all", "UserEvent"=>"LOGVARIABLES"}, @name="UserEvent">

Which corresponds to the AMI this way:

Event: UserEvent Privilege: user,all UserEvent: LOGVARIABLES invoice:yes

So, two things here:

1. We need to ensure we document how to use custom events on the Wiki for Adhearsion to be done properly
2. We need to ensure that the Ragel parsing is more robust so that it drops events not understood and moves on to the next one, as opposed to not parsing anything going forward