Fix compilation with GCC 4.4.
Get rid of a U+0027 APOSTROPHE used where U+2019 is expected
WML style cleanup
fixup typography of some dashes in the "terrains" help section
rewrite a phrase in the help -> terrains page

"help page of the unit" -> "the unit's help page",
using unicode apostrophe.
make a hyphen to unicode in the help > traits page.
Merge branch 'master' of git://github.com/wesnoth/wesnoth