Added a quick joystick control

I'm still not sure whether having a joystick control is the best way to
go, though. We can still try different things.

Also increased the default startup resolution to 1280x720 to match the
common mobile phone resolution.
Added --server and --port arguments

Allows to skip the server selection page.
Added support for tile offset
Removed the usage of probes from qbs for now

QtCreator is currently shipped with a bugged qbs release resulting in
probes erroring.

Revert this as soon this is fixed.
Removed all qDebug() calls for debugging usage

They only help while developing/testing a single feature anyway. You can
just readd them temponary then (and profit from less spam since others
calls are gone).
qbs: Fixed reference to qmldir and ServerListModel.qml
Increased minimum Qt version to 5.1

This allows us to start using Qt Quick Controls and to rely on certain
bugfixes.
Reduced default window size again

Changed it back to what it was since that ensures the existing UI is
still usable, while it doesn't fit nicely on 640x360 (half the target
resolution).
Changed Button to a styled Qt Quick Controls Button

Looks exactly the same but the behavior is now provided by Qt Quick
Controls.
Changed LineEdit to a styled Qt Quick Controls TextField

Also tweaked the login page controls to use the 'visible' property to
make sure tab key navigation doesn't select hidden controls.
Made sure qmldir and ServerListModel.qml show up in Qt Creator
Added a New Character page

It is now possible to create new characters. Only the name and hair
style are configurable for now.

The 'Character' can now be created in QML and the gender, hair style and
hair color can be modified from QML. This allows re-using the same
display method used for in-game characters on the New Character page.
Removed two no longer needed workarounds

Since we now require Qt 5.1.0 we can rely on the related bugs to be
fixed.
Removed code for Qt versions older than Qt 5

Not ever going to be supported again.
Ignore more Qt Creator artifacts
Removed a forgotten Qt 4 line
Create character on pressing Enter / Return in the name edit

Works in addition to pressing the Create button.
Placed the status information in a panel to the left

Can still be toggled with C, but can now also be dragged or clicked into
view with a thin bar that remains visible.
Made the client work on Android again

Required setting the import path and plugin path as appropriate.

The "example" and the "src" projects now use separated QML directories.
This may not have been necessary for Android but I think it is a good
idea anyway.
Smoother camera movement for scaled viewport

The map offset was being rounded to pixels in order to avoid tile
rendering glitches. However, at scale 2 the rounding only needs to be
done at half pixels. So the rounding now takes the current scale into
account.