Fix tab-vs-space in CMake configuration file
Reorder desktop/CMakeLists.txt for more platform-specific clarity
Drop redundant custom_target for po4a
Under MacOSX, generate an Info.plist
Generate an icns icon on Mac OSX
On Mac OS X, write colobot.ini and savegames to Application Support directories
Abstract the definition of DataPath to CSystemUtils
On MacOSX, define the DataPath as being the Resources path in the bundle
On MacOSX, don't cache the Data, Sound and Music paths

As users can potentially move the bundle around, it doesn't make sense to cache these

(It would probably make sense to drop this caching on all architectures, but it's only on MacOSX where it hurts most)
Abstract the definition of LangPath to CSystemUtils
On MacOSX, define the LangPath as being i18n in the Resources path of the bundle
Add MacOSX bundle-specific installation paths
Don't set rpath if libCBot is compiled statically
On MacOSX, install files to Bundle-specific directories
Add MacOSX Bundle and Windows NSIS installer

- Add two images from screenshots or existing data textures to brand the NSIS installer
Update the MXE install README to document the creation of the installer
Add an INSTALL file for MacOSX
On MacOSX, assume we do have CFLocaleCopyCurrent to detect the actual locale by hard-coding the fact in config.h.cmake

This circumvents the fact that we are using localename.c directly instead of relying on the autotools-generated config.h
Enable OpenAL in CI build
Consolidate SYSTEM_CPP_MODULE in the main CMakeLists.txt