fix(Config loading/saving & Application Properties): Improve config loading and saving. Fix the directories to include in server pack setting by loading the correct settings with from a corrected property. Delete you `serverpackcreator.properties`-file to generate a new one.

refactor(ApplicationProperties): Call reloading from constructor to reduce duplicate code and increase maintainability.

refactor(Startup): Rearrange a couple of startup methods. Get rid of the Main-class by moving/merging into ServerPackCreator.class.

improv(File exclusion in ZIP-archives): Make file exclusion opt-out and allow customizing of files to exclude with some basic filter `MINECRAFT_VERSION`, `MODLOADER`, `MODLOADER_VERSION` will be replaced with their respective values.

revert(Tabbed Pane opaque call): Call TABBED_PANE.setOaque(..) not from the constructor, but from createAndShowGUI() to prevent transparent tab-bar.