Precompiling D, and its potential applications

[solidstate1991]

I was thinking about solving (at least) two potholes D's strong 
metaprogramming capabilities cause:

* Use of IDEs and their autocomplete systems. They don't 
immediately break on template functions and types, but don't know 
what to do with mixins and the likes.
* Debuggers, especially when code generation with mixins are 
used, and I have yet to find a debugger that could identify 
templated types and functions consistently.

For solving these issues, an extra functionality of 
precompilation, similar to what C and C++ has, could be added. 
Who knows, this could have extra uses, like debugging for 
metaprogramming.