dynamic memory allocation

[RolfSander]

A lot of values need to be increased in gdata.h and elsewhere (e.g., MAX_EQN) when the chemical mechanism becomes too large. It would be great if KPP would use dynamic memory allocation depending on the size of the chemical mechanism. This is probably a big task, and I don't think I will be able to do it. However, I've created this issue so we can discuss this.

[RolfSander]

Thinking about this feature again, I fear that it won't be possible in C. For the time being, I guess we'll have to recompile KPP every time we reach one of the limits.

I've added the milestone 4.0.0 to this issue.