transpose matrices without numpy
construct stoichiometry matrix without numpy
compute rank of stoichiometry matrix without NumPy
remove numpy dependency from substance adjacency construction
comment out random alpha-beta generator: this method is not used anywhere and needs to be rewritten without using numpy
remove numpy import
update comment
remove global numpy import and make local to method
allow random alpha-beta generator with local numpy import
check that numpy is available and convert alpha and beta to expected numpy.array
numpy not required for basic gratelpy functionality
test on Python 2.6 without numpy
do not assume that matplotlib is available
matplotlib is not required, just optional for drawing