Smoldyn

- Improved graphics and a few other minor changes.

- Minor graphics changes, some improvements in the design of the command queue
for the runtime command interpreter, and it is now possible for commands to
return error messages.

- Cleaned up code for the runtime command interpreter, it is now possible to
save file stacks, minor display and user interface improvements, and several
new commands for text output and excluded volumes.

- A significant bug was fixed in the equation for absorbing walls (thanks to
Dan Gillespie for catching it), it is now possible to pause simulations while
using graphics, and a few minor bugs were fixed.

- Unimolecular reactions can now have much lower reaction rates, a memory error
upon termination was fixed, parameter checking was improved, several minor
bugs were fixed, and two new interpreter commands were added.

- First public release.