timeline gnuplot generation

Hello, Andrey!

I was very happy to find your module, since I actually was going to do the same thing myself (use v8 tools/*.js files) to convert v8.log files.
Thank you for your work!

I think we might use node-tick in WebStorm (https://www.jetbrains.com/webstorm/) to provide node.js/V8 profiling feature. (https://youtrack.jetbrains.com/issue/WEB-1903)
I.e. our application would suggest that users installed node-tick locally and provide us a path, so that our application can use it and interpret the output.

Unfortunately, we are missing 2 things:
1) timeline generation - this is what my patch does
2) and I also would like .11 branch of this module to be provided as a separate tagged version/module, for easy installation.
I can use only .11 branch, since .10 node.js does not support time ticks argument.

If you could fix this issues, it would be wonderful and let us stick to this package as the basis of our solution.
Thank you in advance.


squash this (and next one) into `var LogReader = require('./logreader').LogReader;` ? I don't mind your change to export named constructor property, but really would avoid having variables with only diff in name being case