upgraded build files
added project name to doxygen config
added source note
fixed include path shown in documentation
added tape documentation and default constructor
comleted documentation for tape class
fixed empty string initialization of tape
adjusted build instructions
checks if file is open
added default main for using a dfa
added example dfa
adjusted machine interface
added documentation for machine interface
added documentation for Abstract_Machine class
added documentation for class state
fixed doc
init read with 0 per default
added documentation for transition
added include guard for D_Finite_Automaton
added doc for dfa class