Improve handling of aliased functions

[baldurk]

From discussion on #13 -

For aliased functions (like glUniform3f -> glUniform or glEnablei -> glEnable) it would be useful to have search results match when they are entered, and return the target of the alias function in the search results instead of nothing.

On top of that, if there is a 404 page for when an invalid page is specified (e.g. http://docs.gl/gl4/glNotFound) this page should check to see if the page is an alias source, and if so redirect to the alias target.

[BSVino]

The 404 page I think would have to be set up through the webserver, but if you want to take a stab at it you could assume the page's name to be whatever you please, and then I can change the webserver settings to match that.