Multiple mode changes in one MODE message #93

Altered the MODE message handler to correctly handle multiple mode
changes in one MODE message. It should now corectly display 3 messages
for "`MODE #zoo +vo-o Ape Elephant Ape`" and still display 1 message for
"`MODE #zoo +v Ape`". As mentioned in issue #93.

Please note that there should be tests added for this. I am not sure where to add that, or how to create correct tests in general:

- For the incoming message `MODE #zoo +o Ape`, 1 message event should be sent out with `+o` for `Ape` on `#zoo`. This tests if MODE works correctly for 1 (positive) mode change.
- For the incoming message `MODE #zoo +ov Ape Bear`, 2 message events should be sent out with `+o` for `Ape` on `#zoo` and `+v` for `Bear` on `#zoo`. This tests if MODE works correctly for 2 positive mode changes. Tests if the `+` carries over.
- For the incoming message `MODE #zoo +o-ov Ape Bear Elephant`, 3 message events should be sent out with `+o` for `Ape` on `#zoo`, `-o` for `Bear` on `#zoo` and `-v` for `Elephant` on `#zoo`. This tests if multiple mode changes with positive and negative mode changes work correctly. Tests if the `-` carries over.
- For the incoming message `MODE #zoo +oo Ape`, 1 message event should be sent out with `+o` for `Ape` on `#zoo`. The extra `o` should be ignored. No error should be generated, even though there are more modes than names.
- For the incoming message `MODE #zoo +o Ape Bear`, 1 message event should be sent out with `+o` for `Ape` on `#zoo`. The extra `Bear` should be ignored. No error should be generated, even though there are more names than modes to apply.