isWeaklyReversible -- determines if a network is weakly reversible

i1 : N = reactionNetwork "A <--> 2B, A + C <--> D, B + E --> A + C, D --> B+E"

o1 = A-->2B
     2B-->A
     A+C-->D
     D-->A+C
     D-->B+E
     B+E-->A+C

o1 : ReactionNetwork

i2 : isWeaklyReversible N

o2 = true

i3 : isWeaklyReversible wnt()

o3 = false