Sources here are from lua-5.3.5 (http://www.lua.org/ftp/lua-5.3.5.tar.gz),
with patch 4 for lua-5.3.5 from http://www.lua.org/bugs.html applied.

Not entire lua distribution directory hierarchy is included here, and
some files needed for Freeciv usage have been added.
Changes applied to included lua source files are included in freeciv_lua.patch
