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Update files for 1.7.4.
Update docs/Release.txt.
Set MPC_NIGHTLY_RELEASE to 1.
Fix race warning

CID 1201438
Resolve static initialization order fiasco
StatusBar: less greedy invalidation

Fixes rare flickering.
MainFrame: call OnGetMinMaxInfo() before resize
Cosmetics
SysVersion: use 'static' for local functions