Rudimentary combo box functionality (can be used, but does not yet have the effect of actually switching the resolution).

Squashed commit of the following:

commit b95fb056215fa7c878f337e09b676753d2bd26a1
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Thu Apr 17 02:11:14 2014 +0200

    showing the selection even in the active state.

    The current way that selections are displayed is a little unusual (because we can't go "up" on the screen for now), but it works.

commit c11b0529362e0c3ce7954b97f3bebf8b87a70213
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Thu Apr 17 02:06:50 2014 +0200

    selection is updated in the inactive state. TODO: somehow show the selection even when in the active state (without going upwards / towards negative y, because we would be overlapping with the other button, which we can't handle right now).

commit 922dc309401f3b2e547955961f8619758c7ea616
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Thu Apr 17 01:59:30 2014 +0200

    convert selection index into actual selection [text]

commit 24dbbc773700ee8544d4eba8fbc459a2e2bf8f46
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Thu Apr 17 01:58:12 2014 +0200

    detect which of the choices is selected

commit b5883c9d19873d6b07bb0cd406e4097e966b59fe
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 16:54:31 2014 +0200

    popping up the list and hiding it seems to work appropriately now

commit d1397e33b200cf1a4aa06fd7a73cb9245bd7fcd6
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 16:51:09 2014 +0200

    track the "id" of the combo box within the current gui, instead of just true/false

commit bcb8a6b055083e41f48e5e5927317d5e2b630c0a
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 16:47:01 2014 +0200

    tracking combo box state (this might fail when we have more than one
    combobox).

commit 70c1404bd791c9572fa940c7f39a2dd27ded46ff
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 13:20:11 2014 +0200

    starting to track the mouse button state in the appropriate region of the combobox

commit 78a75ca4ed7fec19f48a5097d08a16d9b3b5fc58
Merge: 144aea9 dba8ca0
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 08:54:21 2014 +0200

    Merge branch 'master' into feature/combobox

commit 144aea97bc82f7842d475b99ff9b41c4211e7b86
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 02:02:41 2014 +0200

    yet another option just for fun

commit 05161fab623145f019b53b81a0da2409759903f5
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:58:53 2014 +0200

    generalized the display of the combo box options

commit c03640c1684bd51f18e0bc40f0a775c793baeae9
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:55:12 2014 +0200

    used the actual resolutions as text

commit f417a3d364c81e7f0f1f0b401fac107c3ec9e8fc
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:54:10 2014 +0200

    draw the rectangle around the original text

commit e304e97f37c81e00e24b2a6e649eb9018fc4b9ea
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:51:15 2014 +0200

    more text gets displayed when combobox is selected

commit 29adeef98bd0592acd4d900c2fc6c1e9e56b1ca3
Merge: c70b4b4 00e7d9a
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:26:36 2014 +0200

    Merge branch 'master' into feature/combobox

commit c70b4b4ffc1542194f25788290221cbde1512119
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:25:06 2014 +0200

    deactivates combo box when mouse is released within the bounds of the "minimized" combo box.

    (TODO: handle the cases properly in which the mouse button is released completely outside, and obviously when it is released on a different selection (for that we need to show the other possibilities first).

commit fceecbd1991c02fdea621d0fcba23ca458a99c2d
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 01:21:31 2014 +0200

    just ignoring the file I use to start the game locally

commit dcb78970bb1a0555c1294814569e8e544251d0b5
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Wed Apr 16 00:57:28 2014 +0200

    reminder

commit 1b2994da8f7d927d51f8113f1d9d63965d08cfe1
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 18:21:12 2014 +0200

    we can react to getting clicked

commit 9687fa776b9f7f902043aab321385362292cca53
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 18:10:08 2014 +0200

    showing the current state (text) of the combo box

commit 2cee2160573f049258b39dbad1e703c000ad15a3
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:59:32 2014 +0200

    jump right into video display settings

commit 1280141812307f912a027071cc1103921ee456ac
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:54:01 2014 +0200

    fixed git/merge artifact

commit 4a48602e61a9f8037698fa79d16dc3dc8bb594fc
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:52:35 2014 +0200

    fixed git/merge artifact

commit a52350fcd437fa39dc8dd780ebc5683ff5410fbe
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:51:20 2014 +0200

    fixed git/merge artifact

commit 3017b9a5eb70a020d8ceb9ac3d3163fec769ba83
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:49:09 2014 +0200

    merge?

commit 1a0bd54266a99d8a96aafac89823272176585e77
Merge: 74ae84d ece43c8
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Tue Apr 15 17:48:25 2014 +0200

    Merge branch 'master' into combobox

    Conflicts:
    	love2d/main.lua
    	love2d/state/settings_video_display.lua

commit 74ae84d0cebd60c35916bbf38a3ec4612cb4e06c
Author: Nicolai Czempin <nicolai.czempin@gmail.com>
Date:   Mon Apr 7 10:15:01 2014 +0200

    first dummy combobox