Qt client: Get the label on a spy action button from its action structure

See patch #4579

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24613 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
SDL clients: Get the label on a spy action button from its action structure

See patch #4580

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24614 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Xaw client: Get the label on a spy action button from its action structure

See patch #4581

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24615 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Gtk clients: Add a mnemonic for the spy action Industial Espionage

like the other spy actions have.

See patch #4583

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24616 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Look for translatable strings in common/actions.c

See bug #21756

git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24617 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Link sdl2-client against external libsdl2-gfx instead of having sources included.

See patch #4570


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24618 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Fixed AI paratrooper and hunter crashes caused by reversed can_unit_attack_tile()
checks.

See bug #21733


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24619 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Separated musicset from soundset.

See patch #4559


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24622 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added gui-specific function insert_client_build_info() that help system calls
to get gui-specific build information part to "About Freeciv" help entry.
gtk-client provide gtk version numbers there.

See patch #4565


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24623 a0f10bec-cc02-0410-94fc-a9cfff90b4cd