Try to recognise unknown hotkey mappings using SDL2.

This improves our international keyboard until we completely rework the
hotkey system which seems to be quite legacy at this point.

Reviewed by Itms.
Differential Revision: https://code.wildfiregames.com/D303
This was SVN commit r19624.

binaries/data/config/keys.txt

@@ -1,5 +1,7 @@
 ## This file documents keynames that can be used in .cfg files for specifying hotkeys
 ## Note: the keynames are not actually configured or implemented here
+## Also note: if your keyboard supports keys that do not appear here (such as the French é letter),
+## you should be able to use it directly.
 
 Backspace, BkSp
 Tab
@@ -150,101 +152,3 @@ Mouse Wheel Down, WheelDown
 MouseButtonX, MouseNX # where X is a number 1-255, for extra mouse buttons
 ## (note that some mice start numbering their buttons at higher numbers
 ##  so the first extra button on your mouse might be #8 here)
-
-## Special keys for international and non-QWERTY keyboards:
-World0, W0
-World1, W1
-World2, W2
-World3, W3
-World4, W4
-World5, W5
-World6, W6
-World7, W7
-World8, W8
-World9, W9
-World10, W10
-World11, W11
-World12, W12
-World13, W13
-World14, W14
-World15, W15
-World16, W16
-World17, W17
-World18, W18
-World19, W19
-World20, W20
-World21, W21
-World22, W22
-World23, W23
-World24, W24
-World25, W25
-World26, W26
-World27, W27
-World28, W28
-World29, W29
-World30, W30
-World31, W31
-World32, W32
-World33, W33
-World34, W34
-World35, W35
-World36, W36
-World37, W37
-World38, W38
-World39, W39
-World40, W40
-World41, W41
-World42, W42
-World43, W43
-World44, W44
-World45, W45
-World46, W46
-World47, W47
-World48, W48
-World49, W49
-World50, W50
-World51, W51
-World52, W52
-World53, W53
-World54, W54
-World55, W55
-World56, W56
-World57, W57
-World58, W58
-World59, W59
-World60, W60
-World61, W61
-World62, W62
-World63, W63
-World64, W64
-World65, W65
-World66, W66
-World67, W67
-World68, W68
-World69, W69
-World70, W70
-World71, W71
-World72, W72
-World73, W73
-World74, W74
-World75, W75
-World76, W76
-World77, W77
-World78, W78
-World79, W79
-World80, W80
-World81, W81
-World82, W82
-World83, W83
-World84, W84
-World85, W85
-World86, W86
-World87, W87
-World88, W88
-World89, W89
-World90, W90
-World91, W91
-World92, W92
-World93, W93
-World94, W94
-World95, W95

source/ps/Hotkey.cpp

@@ -75,6 +75,8 @@ static void LoadConfigBindings()
 			{
 				// Attempt decode as key name
 				int mapping = FindKeyCode(*it);
+				if (!mapping)
+					mapping = SDL_GetKeyFromName(it->c_str());
 				if (!mapping)
 				{
 					LOGWARNING("Hotkey mapping used invalid key '%s'", hotkey.c_str());