Add erltrek_calc.erl

* Split course calculation function to a new module
Update erltrek_klingon.erl

* Split sector_distance/2 to erltrek_calc module
Update erltrek_move.erl

* Split course_distance/4, destination/4, track_course/4 to erltrek_calc module
Update erltrek_event.erl

* Add phaser command in enterprise_command/1
Add erltrek_phaser.erl

* Enterprise phaser control module
Add erltrek.app.src

* Add erltrek_calc and erltrek_phaser modules