First Fit works

1. Replace array with vector(ability to resize)
2. occur changes from bool to int for easier searching
3. rename var head in reconstructs to avoid confusion
4. Minor adjustment everywhere due to the change of occu
5. Implementation of printMemory
6. Implementation of first fit alloc
7. move comments after a line of codes instead of a new line
8. Remove all MessageBox Bug
9. hide all next fit and best fit lines in main for now