New Features

MultiState capability, which enables a single Monomer site to be specified with multiple states (documentation) (#410)
ScipyOdeSimulator multiprocessing capability, using n_processors argument (documentation) (#395)
Multi-GPU simulations and chunking support (split large simulation sets into GPU-sized blocks) for CupSodaSimulator (#409)
Sensitivity analysis class can now work for model parameter sweeps, in addition to initial conditions (documentation) (#426)
Support for fixed concentration species (#364)
Initial condition and parameter sets can now be supplied to Simulator instances as Pandas DataFrames (#416)
Drug binding macro pysb.macros.drug_binding() (documentation) (#387)
Support BngSimulator early stopping using stop_if kwarg (example: sim.run(stop_if='ObsA>9')) (#407)
BioNetGen importer improvements, including preserving parameter depdendencies in expressions, the MoveConnected keyword, and Observables' species compartments (#406)

Improvements

ScipyOdeSimulator is now faster when using Cython due to customized compiler directives (#403)
When model components experience a validation error on creation, they're no longer added to the model by the SelfExporter (#431)
Use the system PATH variable to help find external tools like BioNetGen or Kappa (#389)
SBML Exporter: preserve parameter dependency in initial conditions (#417) and specify initial concentrations for all species (#420)
BioNetGen importer now allows relative paths (#432)
StochKit log file contents are now included in error messages (#429)
Clearer error messages when Cython is non-functional on Windows (#402)

Corrections to the PySB tutorial (#422)
Fix number of simulations calculation for NFsim (#445)
Fix cupSODA when using models with non-alphanumeric characters (#404)
Fix Exception when calling expand_obs() on observables which match no species (#418)
Fix for model name being changed in unit test (#399)
Fix Model.update_initial_condition_pattern (#446)
Minor packaging fixes (#396, #411, #433)
Minor code tidy-ups (#405, #436)
Documentation build fixes (#424, #444)