Planned improvements in MathDrag'n

This is just an introductory list. We will add more things as we think of them.

• Adding more external kernels so that you are not locked in to any particular CAS
  
• Adding the ability to clone equations so the same equation can be taken different directions.
• Adding the ability to handle discrete and continuous sets. This will help us implement integrals and sums.
• Creating a useful, general assumption handler (probably a dialog box) which can let the user either select a predefined set a variable is a member of (e.g. positive or real) or enter their own (e.g x>4, x=2*pi*n).
• Adding the ability to recognize and apply function identities. This is especially important because it means the user could right-click on an expression and see a list of common function identities that could be applied, and pick one.
• Improve the synchronization between equations. This means that if equation one is substituted into equation two, and then the user tries to delete the equation one, MathDrag'n will warn the user that equation two may not be valid after the change and give the user a choice of going ahead anyway, cancelling the deletion, or "rewinding" equation two to where it was before the substitution.