JD2: Add and improve native multihoster support
|Target version:||030 - Version > 2.xxx|
Add new exceptions to support multihoster specific events.
- create an event to return to the next possible download method, without the need to remove getHost() from multiHostSupport array.
Retry event specific to a given multihoster, when over a given threshold return to the next possible download method. So that we don't need internal plugin management of retry counts and the need to remove getHost() from multiHostSupport array.