Plus42 Equations, Preview Release

[Thomas Okken]

New update:

1. When a function without a top-level = sign is selected in the solver, now showing a white EVAL button in the variables menu, which will simply EVAL the function, without trying to solve it.
2. Better parse error checking for array element lvalues in L().
3. Made sure that Invalid Type errors on array literal elements are highlighted on the element in question.
4. Made PRINT menu sticky for all functions.
5. Some memory allocation failure handling (more work still needed in this area).

I think that's it for equations. There is still a bit of work to be done behind the scenes: memory allocation failure handling during parsing and code generation, stress testing with large numbers of equations, bug fixing, and minor tweaks, but as far as functionality and user interface are concerned, I think this is ready.