Fixed units.ruleset documentation comment for veterancy move bonuses not to
consider number of move fragments to be hardcoded as 3, but configurable.

See patch #4676


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24855 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Added mention about government prod/trade bonus changes for alien ruleset
in README.ruleset_alien. 

See patch #4677


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24857 a0f10bec-cc02-0410-94fc-a9cfff90b4cd
Replaced tile_index() function calls with a macro.

See patch #4678


git-svn-id: svn://svn.gna.org/svn/freeciv/trunk@24859 a0f10bec-cc02-0410-94fc-a9cfff90b4cd