gui: Show encodings available with iconv in file editor preferences. * liboctave/wrappers/iconv-wrappers.h, liboctave/wrappers/iconv-wrappers.c (octave_iconvlist_wrapper, octave_iconv_canonicalize_wrapper): Add wrappers for libiconv functions. * liboctave/util/oct-string.h, liboctave/util/oct-string.cc (octave::string::get_encoding_list): Add new function that returns an ordered list of canonicalized encoding names that are available from libiconv. Use list of encoding identifiers as fallback on platforms without the required funcions. * libgui/src/gui-settings.cc, libgui/src/gui-settings.h (octave::gui_settings::get_codecs): Remove function. (octave::gui_settings::combo_encoding): Show list of encoding names that are actually available to the interpreter instead of a list of encodings available in Qt. * libgui/src/qt-interpreter-events.cc (octave::qt_interpreter_events::gui_preference_adjust): Remove logic for mapping between Qt encoding names and iconv encoding names. * libgui/src/settings-dialog.cc: Remove unused header. * m4/acinclude.m4 (OCTAVE_CHECK_ICONVLIST, OCTAVE_CHECK_ICONV_CANONICALIZE): Add checks for functions from libiconv that are not available on all platforms. * configure.ac: Call new functions.

%% this script is intended to be Matlab compatible
%% first, run the script
%
%%   ./build_bc_overloads_tests.sh overloads_only
%
%% to generate the overloaded functions.
%
ex.double = 1;
ex.single = single (1);
ex.logical = true;
ex.char = 'char';
ex.int8  = int8 (1);
ex.int16 = int16 (1);
ex.int32 = int32 (1);
ex.int64 = int64 (1);
ex.uint8  = uint8 (1);
ex.uint16 = uint16 (1);
ex.uint32 = uint32 (1);
ex.uint64 = uint64 (1);
ex.cell = {};
ex.struct = struct ();
ex.function_handle = @numel;

f = fieldnames (ex);
n = numel (f);

fid = fopen ('bc_overloads_expected','w');
fid
for i = 1:n
  for j = 1:n
    s = tbcover (ex.(f{i}), ex.(f{j}));
    fprintf (fid, '%s %s %s\n', f{i}, f{j}, s);
  end
end
fclose (fid)