automatic browser feature detection

[jodeleeuw]

In theory, jsPsych should be able to know if a browser is capable of running a particular experiment automatically.

Each plugin should have a custom feature detection routine to check for features that are relevant to that plugin. The core library can then have a method that runs the feature detection routines of all loaded plugins, so that all the programmer has to do is something like:

jsPsych.checkCompatibility()

More info here: http://learn.jquery.com/code-organization/feature-browser-detection/

[jodeleeuw]

More here as well: http://jibbering.com/faq/notes/detect-browser/

[jodeleeuw]

See #2209