Some modifications to filter and radar simulator

1)FilterPanel.java
- Changed radio buttons to check box objects;
- Changed filter option from int to boolean[].

2)VMS.java
- Modified filterData() method to reflect changes in FilterPanel.java.

3)RadarSimulator.java
- Added methods calculateSpeed(), calculateCourse(), calculateDistance();
- Added conditions to enforce constants MAX_BOATS and MIN_TIMESTEP in methods ini() and addVessel().