Resize and keep aspect ration

Only OpenGL mode has been taken into account.
New options:
keepAspectRatio, boolean
cursorInBlackBandsInFullscreen, boolean
cursorInBlackBandsInWindow, boolean
cursorInBlackBandsInBorderlessWindow, boolean
Keep aspect ratio with no OpenGL

Now the "keep aspect ratio" feature functions even when OpenGL is not employed.
Stop adding visible unit buttons after tenth enemy
Further visible enemy button tweaks
Merge pull request #640 from cfailde/bug261

Stop adding visible unit buttons after tenth enemy
Let player prehear sound settings in options screen

.. rather than the current set volumes then click ok to hear the
difference repeat until satisfied approach.
Fix build on Ubuntu since yaml-cpp 0.5 upgrade.

Thanks to sjamaan for help on #OpenXcom, and this Stack Overflow question for the solution: http://stackoverflow.com/questions/3128497/compiler-error-coming-out-of-yaml-cpp
Merge pull request #641 from cfailde/prehear

Let player prehear sound settings in options screen
Merge pull request #642 from evktalo/master

Fix build on Ubuntu since yaml-cpp 0.5 upgrade.
Fix units being saved from zombification by player saving game

as currently the necessary information is not being recorded in the save
file
Merge pull request #643 from cfailde/zombie_fix

Fix units being saved from zombification by player saving game
Experimental options cause UI issues? Naaaaaaah
Debug coordinates
because default value for _selector is 0.
Merge pull request #644 from redv/fix_textlist

Fix: Crashes of the game.
Disable buttons while player's units are panicked or berserk

so player for example cannot
- access inventory to drop dangerous weapons
- save which can result in a weird mid panic/berserk state that may
cause the game to hang
Merge pull request #645 from cfailde/allow_buttons_fix

Disable buttons while player's units are panicked or berserk
Update soldier info after handling panicking

seeing as disabling buttons while handling panic broke showing soldier
info at the start of a player's turn.
Merge pull request #647 from cfailde/repairInfoUpdating

Update soldier info after handling panicking
Fix initialising battlescape