A sightly modified patch from Raghavendra Prakash for "In version 10.04 - After clicking on lookup, display login page again" https://issues.apache.org/jira/browse/OFBIZ-4937

Step 1: Login - https://localhost:8443/catalog/control/main; Login with credentials
Step 2: Now, select Category lookup; Lookup popup appears; Just get rid of the popup
Step 3: Next, select 'Party' menu item from application tab; You will see the login page again.
Cause: externalKey becomes stale.

I have fixed the issue with a small work around:
externalLoginKeysWR - contains the userLogin for externalLoginKey from app-level tabs
Logic behind: The userlogin could not be found for the external key after the lookup request handled
by OFBiz. The external key with app level tabs become stale once the lookup request is handled, and userlogin
was removed for app level tabs' external keys. As a work around, this fastmap still maitains association with that
external key. When the userlogin could not be found with external key, it would be searched in this fastmap.
This is accomplished in checkExternalLoginKey and getExternalLoginKey methods

jleroux; After testing, I cleaned Raghavendra's contribution. It's maybe not the best way, but it works.

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/branches/release10.04@1429273 13f79535-47bb-0310-9956-ffa450edef68