Remove packaging.cmake, deprecate test_undo setup, and add new testing infrastructure.

- Delete `packaging.cmake` to streamline build system.
- Deprecate `test_undo` in CMake setup; condition builds on `BUILD_TESTS`.
- Introduce `TestFrontend`, `TestRenderer`, and `TestInputHandler` for structured testing.
- Update `GUIInputHandler` and `Command` for enhanced buffer save handling and overwrite confirmation.
- Enhance kill ring operations and new prompt workflows in `Editor`.

cmake/packaging.cmake

@@ -1,62 +0,0 @@
-# Packaging support
-include(InstallRequiredSystemLibraries)
-
-if (CMAKE_BUILD_TYPE STREQUAL "Debug")
-    set(CPACK_DEBIAN_PACKAGE_DEBUG ON)
-endif ()
-
-set(CPACK_PACKAGE_VENDOR "Shimmering Clarity")
-set(CPACK_PACKAGE_DESCRIPTION_SUMMARY "kyle's editor")
-set(CPACK_PACKAGE_VERSION_MAJOR ${PROJECT_VERSION_MAJOR})
-set(CPACK_PACKAGE_VERSION_MINOR ${PROJECT_VERSION_MINOR})
-set(CPACK_PACKAGE_VERSION_PATCH ${PROJECT_VERSION_PATCH})
-
-###################
-### DEBIANESQUE ###
-###################
-if (${BUILD_GUI})
-    set(CPACK_COMPONENTS_ALL gui nox)
-else ()
-    set(CPACK_COMPONENTS_ALL nox)
-endif ()
-
-set(CPACK_COMPONENTS_GROUPING ONE_PER_GROUP)
-set(CPACK_DEBIAN_ENABLE_COMPONENT_DEPENDS ON)
-set(CPACK_DEBIAN_PACKAGE_SECTION universe/editors)
-set(CPACK_DEB_COMPONENT_INSTALL ON)
-
-set(CPACK_DEBIAN_PACKAGE_MAINTAINER "K. Isom")
-set(CPACK_PACKAGE_nox_DESCRIPTION_SUMMARY "kyle's editor")
-set(CPACK_PACKAGE_nox_DESCRIPTION ${CPACK_PACKAGE_DESCRIPTION})
-set(CPACK_PACKAGE_nox_PACKAGE_NAME "kte")
-set(CPACK_DEBIAN_nox_PACKAGE_NAME "ke")
-
-if (BUILD_GUI)
-    set(CPACK_PACKAGE_gui_PACKAGE_NAME "kge")
-    set(CPACK_DEBIAN_gui_PACKAGE_NAME "kge")
-    set(CPACK_PACKAGE_gui_DESCRIPTION_SUMMARY " graphical front-end for kyle's editor")
-    set(CPACK_PACKAGE_gui_DESCRIPTION "graphical front-end for ${CPACK_PACKAGE_DESCRIPTION} ")
-endif ()
-set(CPACK_DEBIAN_PACKAGE_SHLIBDEPS ON)
-set(CPACK_DEBIAN_PACKAGE_GENERATE_SHLIBS ON)
-
-
-if (LINUX)
-    set(CPACK_GENERATOR "DEB;STGZ;TGZ")
-elseif (APPLE)
-    set(CPACK_GENERATOR "productbuild;TGZ")
-elseif (MSVC OR MSYS OR MINGW)
-    set(CPACK_GENERATOR "NSIS;ZIP")
-else ()
-    set(CPACK_GENERATOR "ZIP")
-endif ()
-
-set(CPACK_SOURCE_GENERATOR "TGZ;ZIP ")
-set(CPACK_SOURCE_IGNORE_FILES
-        /.git
-        /.idea
-        /dist
-        /.*build.*)
-
-include(CPack)
-cpack_add_component(gui DEPENDS nox)