Eliminated Delays + Restructured Flow

Modified flow such that when keys are pressed for the different modes
(collecting neutral, collecting pro/sup samples, collecting dynamic),
the appropriate command is written to the port and then serialEvent()
calls collectNeutral(), collectPro(), collectSup(), depending on which
key was pressed.

-The 10 sample arrays are now populated element by element rather than
after all 10 have been written from port.  Global variable j used for
incrementing

-Introduced variable "mode" that is defined when keys are released and
checked by serialEvent()