Split init and exit in the two mediastreamer libraries to prevent undefined reference errors at compilation on some systems.

Add function to check if an ICE check list can be set to the Completed state after adding the losing pairs.

Do not use the nominated valid pairs with the highest priorities, used the selected pairs instead.

Add accessors to get the number of check lists in an ICE session and to remove a check list from it.

A pair must become nominated only once a connectivity check with the USE-CANDIDATE attribute has been successful.