add osxapp target

Not fully tested.

ui-macos/git-annex.app/Contents/MacOS/runshell

@@ -0,0 +1,44 @@
+#!/bin/sh
+set -e
+
+base="$(dirname $0)"
+
+if [ ! -d "$base" ]; then
+	echo "** cannot find base directory (I seem to be $0)" >&2
+	exit 1
+fi
+
+if [ ! -e "$base/bin/git-annex" ]; then
+	echo "** base directory $base does not contain bin/git-annex" >&2
+	exit 1
+fi
+if [ ! -e "$base/bin/git" ]; then
+	echo "** base directory $base does not contain bin/git" >&2
+	exit 1
+fi
+
+# Get absolute path to base, to avoid breakage when things change directories.
+orig="$(pwd)"
+cd "$base"
+base="$(pwd)"
+cd "$orig"
+
+# Put our binaries first, so our overloaded libs don't get used with
+# system binaries.
+# Also avoids issues with out of date system binaries.
+PATH=$base/bin:$PATH
+export PATH
+
+DYLD_LIBRARY_PATH=$base/lib:$DYLD_LIBRARY_PATH
+export DYLD_LIBRARY_PATH
+
+GIT_EXEC_PATH=$base/git-core
+export GIT_EXEC_PATH
+
+if [ "$1" ]; then
+	cmd="$1"
+	shift 1
+	"$cmd" "$@"
+else
+	$SHELL
+fi