Documentation improvements

[pstjvn]

I like very much the idea behind your work and I used parts of the framework, however based on my experience with closure library for the last 2 years I find for myself that the best way to understand how to use something is to read its code and documenting comments. What I see in your work is mostly annotations for the compiler and very little information on the actual methods and the idea behind them, let alone description of why a certain method is working the way it is. Most recent example for me is the placeChild_ property that is marked with underscore (while not strictly a compiler directive (i.e. missing private tag) underscore usually indicates private members) it is unclear how to use it nor how to set it. At least setter method should have been provided (if it should be really considered a private member) and description on how it is supposed to be used.

I would really love to see more descriptive and helpful comments in the code, this will greatly reduce the time it takes for a closure developer to get used to your work.