Added initial simulation

Functions:
- Gates: andGate, orGate, noGate
- isThatAFunction: test if obj is a function
- emptyBioPart: make empty BioPart
- oneSimulation: single simulation step
- Species: Simplified species constructor

Main: Including this for future use?

Test: Has a test case for simple simulation

Types: Unique composite types
- Species: Name, current value, initial value, first initial value
- BioPart: input (two species), gate (should be a function, not sure how
to check), k (currently only constant), output (one species)