Add a SDL2 compatibility wrapper.

This wrapper takes care of the renaming of some types done in SDL2. This
allows better compatibility between SDL 1.2 and 2.0 code.
Rename a function parameter unused -> alpha.

The new name is more appropriate.
Add a fix for the renamed field in SDL2.

The unused field in SDL_Color has been renamed to a.
Port sdl_keysym_from_name for SDL2 usage.

Use the SDL2 function SDL_GetKeyFromName.
PL translation for campain of two brothers
Add a wrapper for SDL_SetAlpha when using SDL2.

The code is only compile-tested. Since there are more compilation issues
the code has not been tested at run-time.
Fix a several event handling loops.

Several events which were normal events in SDL1.2 have been moved as
subevents of the SDL_WINDOWEVENT in SDL2.0.
SConstruct: small typo
Merge pull request #112 from techtonik/patch-1

SConstruct: small typo
Added a macro to sync the minimap region of default and editor theme.
Adjusted some indentations.
Added myself to the credits.
LoW 7: Enlarged the map and adjusted starting positions.
Fix loading of items in the editor beign one hex field off.
Change the interface of map_location's constructor.

Adds a default Null pointer to the signature of map_location created
from a config and a variable_set.
Fix some mess with wrong hidden attributes and hotkey bindings.
Update to the default and editor themes.

Reintroduced the alignment and side.
Micro AIs: add check for valid attacks and error message

This will now check whether the attack intended to be done with
ai.attack is possible and display an error message if it is not.
Micro AIs: add check for valid full move and error message

This now checks whether the move intended to be done with ai.move_full
is possible and display an error message if it is not.
Micro AIs: add check for valid move and error message

This now checks whether the move intended to be done with ai.move is
possible and display an error message if it is not.