feat(macOS): initial macOS bundle support

.gitignore

@@ -6,3 +6,6 @@
 
 # User config file
 CMakeLists.txt.user*
+
+# Why, macOS, why?
+.DS_Store

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.12)
 
-project(pineapple-music LANGUAGES CXX)
+project(pineapple-music LANGUAGES CXX VERSION 0.3.0)
 
 include (GNUInstallDirs)
 include (FeatureSummary)
@@ -67,7 +67,7 @@ set (EXE_NAME pmusic)
 file (GLOB PMUSIC_TS_FILES languages/*.ts)
 set (PMUSIC_CPP_FILES_FOR_I18N ${PMUSIC_CPP_FILES} ${PMUSIC_UI_FILES})
 
-add_executable(${EXE_NAME} WIN32
+add_executable(${EXE_NAME}
     ${PMUSIC_HEADER_FILES}
     ${PMUSIC_CPP_FILES}
     ${PMUSIC_UI_FILES}
@@ -103,8 +103,23 @@ endif()
 
 # Install settings
 if (WIN32)
-    # FIXME: try to avoid install to a "bin" subfolder under windows...
-    #        when fixed, don't forget to update the CI config file...
+    set_target_properties(${EXE_NAME} PROPERTIES
+        WIN32_EXECUTABLE TRUE
+    )
+elseif (APPLE)
+    set_source_files_properties(assets/icons/app-icon.icns PROPERTIES
+        MACOSX_PACKAGE_LOCATION "Resources"
+    )
+    target_sources(${EXE_NAME} PUBLIC assets/icons/app-icon.icns)
+    # See https://cmake.org/cmake/help/v3.15/prop_tgt/MACOSX_BUNDLE_INFO_PLIST.html
+    set_target_properties(${EXE_NAME} PROPERTIES
+        MACOSX_BUNDLE TRUE
+        MACOSX_BUNDLE_BUNDLE_NAME "Pineapple Music"
+        MACOSX_BUNDLE_GUI_IDENTIFIER net.blumia.pineapple-music
+        MACOSX_BUNDLE_ICON_FILE app-icon.icns # contains the .icns file name, *without* the path.
+        MACOSX_BUNDLE_BUNDLE_VERSION ${PROJECT_VERSION}
+        MACOSX_BUNDLE_SHORT_VERSION_STRING ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}
+    )
 elseif (UNIX)
     if (CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
         set(CMAKE_INSTALL_PREFIX /usr)
@@ -125,6 +140,7 @@ elseif (UNIX)
 endif()
 
 set (INSTALL_TARGETS_DEFAULT_ARGS
+    BUNDLE DESTINATION .
     RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
     LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
     ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Devel