frotz: update to 2.53

This is a minor release focusing on minor enhancements and bug fixes.

NEW FEATURES

- -E option to choose how emphasised text is rendered.

- X11 interface has been added as a compile target.

- Added new default TrueType font for sfrotz.

- Automatically select the appropriate interpreter number for V6 games.

- Limited mouse support for curses interface.

BUG FIXES

- Corrected potential trouble with garbage in filenames for SDL
  interface.

- Corrected a problem wherein @print_table would sometimes print garbage.

- Fixed a segfault problem when input buffers are abused.

- Double-clicks are now recognized in sfrotz and xfrotz.

- Fixed problem with spurious newline when a space triggers a word wrap.

- Fixed a problem with UTF-8 characters getting corrupted during line
  editing.

- Fixed some problems with V3 games scribbling on the status line in
  certain circumstances.

- Removed pre-C99 idioms and C++ comments in curses and core to benefit
  older compilers.  X11 is still pre-C99 clean.  SDL interface is not
  pre-C99-clean due to libSDL2 not being pre-C99-clean.

- Fixed a problem with the -x flag not properly expanding commands for
  some Infocom games.

(nia)