Fix some coverity scan defects

[nico-abram]

• Add move constructor to LuaReference
• Use strncpy instead of strcpy in RageThreads.cpp
• VideoModeParams move constructor in RageDisplay.h
• Change RageDisplay::SetVideoMode to use an rvalue reference
• All the defects I saw in DLMAN
• Fix use of uninit value in RageFileBasic
• Fix use of uninit value in NSMAN
• Fix LuaHelpers::TypeError bug
• Add missing month enum constants
• Fix uninit value in MusicWheel.cpp
• Fix resource leak in HighScore.cpp
• Add missing dynamic cast assertion in MusicWheelItem.cpp
• Add missing dynamic cast assertions in ScreenGameplayPractice
• Attempt to fix coverity defect in PlatformUnix.cpp