Refactor Browser Detection

The current client-side browser detection code is repetitive and needs to be updated with the release of each new browser version each month. This is tedious.

Find and implement a suitable client-side library for browser fingerprinting. The library must be accurate, stable and invisible.

Ideally the library should not append elements to the DOM to identify the browser. This is sloppy, unnecessary, error-prone and not very stealthy.

Hopefully this can be implemented cleanly without too much refactoring. The framework doesn't use the browser version specific functions `isFF33()`, `isFF34()`, etc, very often, however it would be nice to maintain this functionality somehow.