Single-player difficulty selection was implemented in a very hacky way.
Documents what's going on there and fixes a memory leak.
Memory leaks that this fixes looked like this:
```
Direct leak of 64 byte(s) in 1 object(s) allocated from:
#0 0x7f435b789f17 in operator new(unsigned long) (/lib/x86_64-linux-gnu/libasan.so.6+0xb1f17)
#1 0x5567766c62b8 in dvl::selgame_GameSelection_Select(int) ../SourceX/DiabloUI/selgame.cpp:163
#2 0x5567766d8ee8 in dvl::selhero_Load_Select(int) ../SourceX/DiabloUI/selhero.cpp:464
#3 0x5567766d6ed1 in dvl::selhero_List_Select(int) ../SourceX/DiabloUI/selhero.cpp:325
#4 0x556776692683 in dvl::UiFocusNavigationSelect() ../SourceX/DiabloUI/diabloui.cpp:396
#5 0x55677669158e in HandleMenuAction ../SourceX/DiabloUI/diabloui.cpp:223
#6 0x5567766917b9 in dvl::UiFocusNavigation(SDL_Event*) ../SourceX/DiabloUI/diabloui.cpp:277
#7 0x556776695dff in dvl::UiPollAndRender() ../SourceX/DiabloUI/diabloui.cpp:626
#8 0x5567766d94ef in UiSelHeroDialog ../SourceX/DiabloUI/selhero.cpp:512
#9 0x5567766d997f in dvl::UiSelHeroSingDialog(int (*)(int (*)(dvl::_uiheroinfo*)), int (*)(dvl::_uiheroinfo*), int (*)(dvl::_uiheroinfo*), void (*)(unsigned int, dvl::_uidefaultstats*), int*, char (*) [16], int*) ../SourceX/DiabloUI/selhero.cpp:547
#10 0x556776a44f45 in mainmenu_select_hero_dialog ../Source/mainmenu.cpp:98
#11 0x5567765f9f15 in SNetInitializeProvider ../SourceX/storm/storm_net.cpp:102
#12 0x556776c996b9 in multi_init_single ../Source/multi.cpp:826
#13 0x556776c98b1e in NetInit ../Source/multi.cpp:770
#14 0x5567767d0c0b in StartGame ../Source/diablo.cpp:375
#15 0x556776a4493d in mainmenu_init_menu ../Source/mainmenu.cpp:45
#16 0x556776a44c05 in mainmenu_single_player ../Source/mainmenu.cpp:61
#17 0x556776a454a9 in mainmenu_loop ../Source/mainmenu.cpp:152
#18 0x5567767d2892 in DiabloMain ../Source/diablo.cpp:602
#19 0x5567766e3c69 in main ../SourceX/main.cpp:34
#20 0x7f435a69ecb1 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x28cb1)
```
Still missing is the support screen (functionally identical to the
credit screen)
This also fixes a long standing issue with the menu code where it would
some times return the index and some times the value of the selected
menu item. It now always returns the index and reciver must look up the
value.
Fixes#566
The hero is unloaded before entering this screen from a game, hacking
the game to track the hero level would not work with single player
(planned to also have a select screen) so the only proper solution is to
load the info from the save game. Using gszHero allows us to stay synced
with the engine.
Anders Jenbo
Gleb Mazovetskiy
Juliano Leal Goncalves
MrHuu
pionere
qndel
Tyler
BDC
SeanHenderson
Pyr0Byt3