Don't ignore 7z_command.cmake

It probably should be in cmake/ instead of dist/ but this will do for now

.gitignore

@@ -39,6 +39,7 @@
 !/dist/res
 !/dist/CMakeLists.txt
 !/dist/makebuild.ps1
+!/dist/7z_command.cmake
 
 /msvc/*
 !/msvc/resource.h

dist/7z_command.cmake

@@ -0,0 +1,26 @@
+set(7ZIP_COMMAND "${ZIPTOOL_7Z_EXECUTABLE}" a -tzip -mtc- -mcu+ -mx=9 -r "${PK3_DESTINATION}/slade.pk3" .)
+
+if(EXISTS "${PK3_DESTINATION}/slade.pk3")
+	if(WIN32)
+		set(PLATFORM_GREP_COMMAND findstr "/c:SHA256 for data and names:")
+	else()
+		set(PLATFORM_GREP_COMMAND grep "SHA256 for data and names:")
+	endif()
+	execute_process(COMMAND  "${ZIPTOOL_7Z_EXECUTABLE}" h -scrcsha256 .
+		COMMAND  ${PLATFORM_GREP_COMMAND}
+		OUTPUT_VARIABLE FOLDER_SHA256
+	)
+	execute_process(COMMAND  "${ZIPTOOL_7Z_EXECUTABLE}" t -scrcsha256 "${PK3_DESTINATION}/slade.pk3"
+		COMMAND  ${PLATFORM_GREP_COMMAND}
+		OUTPUT_VARIABLE PK3_SHA256
+	)
+	if(FOLDER_SHA256 STREQUAL PK3_SHA256)
+		message(STATUS "slade.pk3 is already up to date.")
+	else()
+		file(REMOVE "${PK3_DESTINATION}/slade.pk3")
+		message(STATUS "Regenerating slade.pk3...")
+		execute_process(COMMAND ${7ZIP_COMMAND})
+	endif()
+else()
+	execute_process(COMMAND ${7ZIP_COMMAND})
+endif()