multi-line comments should wrap at the 120th column

[jbphet]

The current PhET coding convention is that comments wrap at 120 columns, not at 80, as I'm seeing as I start reviewing the code. 120 was agreed upon because most modern screens accommodate it and it allows us to get more code on the screen. For example, this comment in ManualGeneExpressionModel.js

    // List of areas where biomolecules should not be allowed.  These are
    // generally populated by the view in order to keep biomolecules from
    // wandering over the tool boxes and such.

should instead be

    // List of areas where biomolecules should not be allowed.  These are generally populated by the view in order to 
    // keep biomolecules from wandering over the tool boxes and such.

...which takes up fewer lines.

Please go through the code and format all multi-line comments to match this convention.

[aadish]

fixed closing