Windows changes: Install plugins into lib/ not into plugins/. Don't link against libiconv when compiling against GLib 2.14 and above (it's statically linked into GLib). Install Geany's message catalogs into share/locale rather than lib/locale as GTK does since 2.12.2.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@2673 ea778897-0a13-0410-b9d1-a72fbfd435f5