[NEW] Add "Set Updater proxy..." command for setting the proxy of updater.
[BUG_FIXED] Warn user if current document is read only while replacing operation.

git-svn-id: svn://svn.tuxfamily.org/svnroot/notepadplus/repository/trunk@1022 f5eea248-9336-0410-98b8-ebc06183d4e3