Compare two PresenceTypes.
0 will be returned if the types are equal, a positive number will be returned if type_a is more available than
type_b, and a negative number will be returned if the opposite is true.
| type_a |
the first PresenceType to compare |
| type_b |
the second PresenceType to compare |
|
a number representing the similarity of the two types |
0.1.11