Lots of functionality added to admin panel (as good as finished now).

Hid some unused / not finished and unneccessary fields.

Changed Login to merlin using a prepared statement-

Deleted SpeciesCategoryEnum

Minor changes to scheme_setup.sql example observation data.
Merge branch 'master' of https://github.com/Isaisaisa/DB-Merlin

Conflicts:
	Aufgabe_3/src/merlin/data/SpeciesRepository.java
	Aufgabe_3/src/merlin/gui/MerlinMainWindow.java