Remove GTK mnemonic from two strings used in the Qt client

In the GTK clients an underscore in a label makes the following character a
mnemonic. In the Qt client it gets displayed as common text. The underscore
in the text labeling the buttons for the spy/diplomat actions "Sabotage City"
and "Establish Embassy" is therefore useless in the Qt client.

See patch #4332

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23850 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Do not add "AutoOnCityCenter" extra if there already is conflicting extra
on tile

See patch #4188


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23851 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Include savecompat.h to savegame.c and remove duplicate definitions of
hex_chars, bin2ascii_hex, and ascii_hex2bin

See patch #4328


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23853 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Replaced tile_special_type_iterate() with EC_SPECIAL iteration

See patch #4330


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23854 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added view to default modpack list to Qt version of modpack installer. 

See patch #4333


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23856 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Removed special name related functions from terrain.[ch].
Reimplemented necessary ones to savecompat.[ch] in a way that does not depend on extras
but is backward compatible with old freeciv versions.

See patch #4329


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@23858 a0f10bec-cc02-0410-94fc-a9cfff90b4cd