[UX] Add Device:openLink() stub for Linux SDL

[Frenzie]

References #4821.

[poire-z]

It's minimal for now and non intrusive to other platforms, so probably fine.

But I guess one could still like to see the url in a confirmBox and confirm he really wants to launch a fat web browser to go there.
And more generically, there should probably be a bunch of new submenus in Links>:
Wikipedia links > Ignore | Lookup in KOReader | Open external browser | Wallabag | WhateverOtherPluginThatCouldDoSomethingWithLinks - and why not a checkbox [ ] ask for confirmation.
And the same for External links>.

On Android, I guess it should launch an intent that would be catch by any app able to handle http:// links.

[pazos]

On Android, I guess it should launch an intent that would be catch by any app able to handle http:// links.

It becomes harder on new android versions, but yeah. We need to take a string with url and create a new Uri with http scheme and then start the new activity via intent (we should catch the ActivityNotFound error that triggers if no activity is registered to view that kind of scheme and, optionally, notify the user that no external browser is available via android.notification).

[Frenzie]

@poire-z

It's minimal for now and non intrusive to other platforms, so probably fine.

I don't really know what intrusive could even mean here? :-)

But I guess one could still like to see the url in a confirmBox and confirm he really wants to launch a fat web browser to go there.

I'd say that's a matter for the URL handler, not for KOReader. If the URL handler launches a "fat web browser" that's the user's choice outside of KOReader. (Same for Android.) But sure, some kind of additional setting could be added in the future.

@pazos
I'll try to refrain from commenting on Android, other than stating that it's typical of the system that there should be anything even remotely complicated about opening a simple link post-Windows 95 or so.