+ Add well known access level config for inactive accounts. If this
access level is set, the account is considered to be inactive and the
client does not get a banned response, but a login fail response with
the reason "account inactive".
+ Add the ability to change the default access level of auto created
accounts.

Changed configuration strategy to merge configs.
Updated to Java 14's version of L2J Commons.

Fixed several typos.
Updated L2J Commons to 2.6.3.0.
Updated MMO Core to 2.6.2.0.

Idea taken from
https://github.com/Zoey76/L2J_LoginServer/commit/379e27313faa9421b9f99b18d9f1db5a9c49ea00

Adding hot reloading.
Using static methods for less verbose configurations.
Separated Database configurations into own file (same as Game server).

Ported all to SLF4J.
Refactored package structure.
Added new fluen API for configurations.
Using Maven.