fix: Fixed errors in locating GNU Readline

Signed-off-by: Sebastian Niemann <niemann@sra.uni-hannover.de>
fix: Fixed uninitalised random device

Signed-off-by: Sebastian Niemann <niemann@sra.uni-hannover.de>
fix: Added unimplemented methods and set the pure virtual objective value implemention to const

Signed-off-by: Sebastian Niemann <niemann@sra.uni-hannover.de>
feat: Added first draft for the CLI with GNU Readline support

Signed-off-by: Sebastian Niemann <niemann@sra.uni-hannover.de>