Blockbuffer will always work, even before split_window has been invoked.
Made fizmo_new_screen_size adapt blockbuffer screen size. The blockbuffer is
now automatically created upon startup.

- Merged/adapted set_max_undo_steps().
- Merged opcode_save_undo() changes.
- Fixed segfault in case undo_index == max_undo_steps.
- Adapted get_allocated_undo_memory_size, added size of undo_frames to
  memory amount.
- Adapted free_undo_memory.

- Merged non-NULL z_mem verification in fizmo_new_screen_size().
- Merged non-NULL z_mem check in write_interpreter_info_into_header().
- Merged max-undo-steps evaluation and z_mem-NULL-reset in fizmo_start().
- Fixed erroneous xdg_config_home-NULL-check in fizmo_start().

Added memory cleanup for upper window buffer, z_story and so on, added
explicit initialization of "terminate_interpreter" flag to make multiple
fizmo_start() invocations work.

Fixed a crash that occured during re-enabling transcripting from screen
interfaces implementing "prompt_for_filename". So far streams.c assumued
that once a script file has been opened the filename would always be
stored in "stream_2_filename" which was not the case after invoking
"prompt_for_filename".

Added "disable-stream-2-wrap" to options. This allows us to get rid of
the "wordwrap_output_left_padding" function, since stream-2-wrapping
was the only thing which still required it.

No more raw exit() calls, added screeninterface-specific filename
prompt, new screeninterface-specific filename prompt replaces
fizmo_register_ask_user_for_file_function, fixed
autosave-functionality.

 - Updated changelog for restore-fix.

 - As with restart, the transcription and fixed font bits should survive
   a restore.

 - Updated changelog for empty-path-fix.

 - Fixed an error which would occur for empty pathnames when starting
   up a game on 32-bit platforms, thanks to Samuel Verschelde.

 - Isolated opcode identification into "parse_opcode" function. This wil
   allow the debugger to use this functionality from outside.

 - Fixed bindir for config.default.mk from "bin" to "games".

 - Fixed the fixes for the fixes of $(DESTDIR)-inclusion.

 - Fixed the fixes for $(DESTDIR)-fixes.

 - Fixed $DESTDIR-fixes.

 - Fixed missing $(DESTDIR) installation variable: Should have already
   been in since 0.7.1, but was simply forgotten.
 - Adapted version numbers in code, Makefiles and man pages for new version.
 - Adapted changelogs.

 - Added general story information to debugger commands.

 - Added ENABLE_DEBUGGER variable to default config files.

 - Memory boundary tracelogs.

 - Fix for praxix.z5 fixes.

 - Fixed warning which occured due to DISABLE_PREFIX_COMMANDS.

 - Updated changelog.

 - Updated copyright notices to new year.

 - chmod 644 for "etude.z5".

 - chmod 644 for "etude.z5".

 - Implemented zerf's "DISABLE_PREFIX_COMMANDS" from github.

 - Added forgotten beta postfix to version numbers.