Initial import of version 1.55
handle SDL quit event

This patch makes Jump'n'bump quit when pressing the close button or
using other means to ask Jump'n'bump to quit (e.g. Alt+F4).

See http://bugs.debian.org/487333
Use safe temporary files

This may break Jump'n'bump on Windows.  Maybe the patch should be
cleaned up a bit.

see http://bugs.debian.org/500611
Exit fullscreen mode when you quit

see http://bugs.debian.org/338705
Write output file to current directory, not to the directory of the source files
Pack files with the current basename of the file parameter, not the whole path
CMake based build system
Eliminate all compiler warnings

Make the program compilable -Wall -Wextra and -Werror with current gcc
and clang
Use #include <header> for system header includes and #include "header" for local header includes
SDL2 port
Limit upward movement in jetpack mode to avoid segmentation fault
Fix CMake dependencies
Use SDL Textures instead of surfaces
Remove #ifdef USE_SDL
Set render scale quality hint to "best"
Print renderer name on initialization
Make window resizable
Fix fs_toggle
Support for 16 bit textures
Do scaleup by default