Default configuration rework. Function's aliases move to config.

Hey, Rokas! Once more, thanks for awesome tool!

I developing Kint port for Drupal and i found that there is no possibility to preconfigure Kint default settings from outside of Kint distribution.

For now Kint requires: config.default.php + config.php
How about to create something like this? :
1) Framework's/CMS settings (stored in $GLOBAL['_kintSettings'])
2) config.default.php - on this step fill only parameters that not setted
3) config.php (if it exists) - has higher priority and overrides any configuration property

If i just download Kint distribution and use it in any framework\cms - it should pe possible to use original Kint distribution instead adapted forks and configure should be as flexible as possible, i think.

Also, i think any framework\cms can provide self alias for Kint::dump(), maybe it is more useful to move aliases configuration to config? (that can be preconfigured before Kint is included).

In this pull request i moved aliases definition into config file and in default.config.php at end of file set only not setted config properties.

If you will accept this pull request - i can finish my Drupal module and set one as stable.

Waiting for your response. 
Thanks!