fix: Allow selection of bmp, jpg and jpeg as server-icons. Java correctly converts them to png for use as server-icons. If the image could not be loaded, print an error message.

refactor: Print server-icon and server.properties paths. Re-organize method in CreateServerPackTab to ensure GUI becomes responsible again if the generation of a server pack fails.

refactor: Print server-icon and server.properties paths. Re-organize method in...

See merge request !100

feat: Write errors encountered during config check to logs/console. When using GUI, show a message with the encountered Errors. Helps with figuring out whats wrong with a given configuration.