Merge branches 'dev/stijn' and 'master' into dev/stijn
Implemented exceptions. (but to be tested yet)
small semantic error fixed.
DFA fully tested.
using empty method instead of comparing empty string.
enfa fully tested.
extended tests of extended_transition of enfa
nfa tested.
added some throw tests to dfa() method
Merge branches 'master' and 'dev/stijn'