Fixed random seed from clock and id-check.

Added a new parameter to particle: ID just an int describing when this
was added in creation. Id is same as index in objects list. Pro? Can use
it to identify so that force is not found from itself.

Also, corrected problem when seed was drawn from system clock.
main.cpp: Fixed standard dt arg.
Added check for bound object.

Also updated reader to read in number of bound particles per time step.