Sync patches r14614, r14624, r14625, r14673 and r14727 from main trunk.
1. Update sample code for date/time.
2. Enable warningif opcode in browser.
3. Refine question value update logic.
4. Use RETRIEVE instead of CHANGING for refresh question.

git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1/MdeModulePkg@14728 6f19259b-4bc3-4df7-8a09-765794883524
Sync patch r12929 from main trunk.
Correct definition to follow spec.

git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1/MdeModulePkg@14729 6f19259b-4bc3-4df7-8a09-765794883524
Sync patches r14451, r14452, r14453 and r14474 from main trunk.
Update HiiDataBase and  UefiHiiLib to support Name/Value varstore. 



git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1/MdeModulePkg@14732 6f19259b-4bc3-4df7-8a09-765794883524