Further refinements of the comments

Continued the great work that was started by Joshua Anderson. Joshua - what do you think about these changes? I tried to trim out some extra white space, but also improve the grammar a bit. (For example, method summaries should always have "Performs work related to foo" IMHO, not "perform work related to foo", which is also how [Microsoft does it at MSDN](http://msdn.microsoft.com/en-us/library/ms131262%28v=vs.110%29.aspx).

I also did other adjustments, which you can see in the diff. If you like, you can merge these changes into your PR and I can then merge the completed PR into the CefSharp repo. Thanks for your good improvements! We can definitely do more in this area (and we should also do the same for CefSharp3, btw).