Remove region/host defaults, add apimode tanks/planes, setRegion changes

Incompatible changes:

Default Region and host removed.

baseHost renamed to host. $host will always contain the full hostname now.

setting a Region will remove the customhost bool.

setApiMode now required.

either: setRegion or setHost now required.

official wargaming hostnames are generated in setRegion.

```
$client->setApiMode(Client::TANKS);

$client->setRegion(Client::REGION_RUSSIA);
$client->setHost('example.ru')
```