We now allow you to download files by right-clicking a link and then
choosing "Download".
All files are currently saved to the standard downloads location that
we get from Core::StandardPaths::downloads_directory().
In the future, we'll probably want to come up with a more restrictive
way of doing the "write to disk" portion of this.
We should also improve the ProtocolServer to allow streaming of data
instead of writing everything in one big go.
At the moment, I'm just pretty happy with this GUI. :^)
Note that this is a little bit unreliable with the keyboard shortcut
since LibGUI can get confused about which Action it's supposed to use
as each Browser::Tab has its own "close tab" action. This will need
to be fixed in LibGUI.
This patch moves most of the Browser UI into a Tab class. The main UI
now mainly consists of a GUI::TabWidget that Tab objects are added to.
I'm going with the "tabs on top" style here, since I like how it makes
it feel like each tab has its own UI controls (which it actually does!)
