Rename TortoiseIDiff/resources to TortoiseIDiff/Resources being consistent with src/Resources.

git-svn-id: http://tortoisesvn.googlecode.com/svn/trunk/src/TortoiseIDiff@24775 4cfb86a4-2c7a-11df-bd14-c1e331e6ceac
Check that there's a second pic before trying to access it.

git-svn-id: http://tortoisesvn.googlecode.com/svn/trunk/src/TortoiseIDiff@24789 4cfb86a4-2c7a-11df-bd14-c1e331e6ceac