Add test functionality for available substrates
Optimized test function and added doc
Added substrates to modules

These will hold initial values
Amended substrates config to lipid
Added DNA module
Test only succeeds if non negative
Added Transporter module
Generator functions for transporter int and ext
Added Metabolism module
Added Protein module
Auto add substrates on run. Default cell module
Cell has to have at least one sub to grow
Renamed files for require tree

Base classes are named class._. Derived classes are named class.derived.
This way, requiring the tree ALWAYS works
Added CellGrowth module
Fixed cell spec
Namespacing sweetsticks
Fixed metabolism step function
Fixes for the modules
Added tree and node classes
Reimplemented undo with tree