Rename `depth-bound-description-graph' to `prune-description-graph'

Signed-off-by: Daniel Borchmann <daniel.borchmann@mailbox.tu-dresden.de>
Whitespace fix

Signed-off-by: Daniel Borchmann <daniel.borchmann@mailbox.tu-dresden.de>
Converting description trees to EL concept descriptions

Signed-off-by: Daniel Borchmann <daniel.borchmann@mailbox.tu-dresden.de>