seibu/t5182.cpp: Remove hardcoded tags, Cleanups:

[cam900]

• Use DERIVED_CLOCK for Z80 clock input
• Fix spacing
• Correct typename for variables
• Use C++ style comments for single line comments

seibu/darkmist.cpp: Cleanups

• Reduce literal tag usage and runtime tag lookups
• Reduce unnecessary lines
• Fix spacings

seibu/metlfrzr.cpp: Cleanups

• Reduce literal tag usage and runtime tag lookups
• Constantize variables
• Fix spacing
• Fix ROM region namings
• Use C++ style comments for single line comments
• Fix filename in comment

seibu/mustache.cpp: Cleanups

• Fix spacing
• Fix main CPU ROM region size

seibu/panicr.cpp: Cleanups

• Fix typo in comment
• Reduce preprocessor defines
• Reduce literal tag usages and runtime tag lookups
• Use mark_tile_dirty for text tilemap layer mark dirty method
• Fix screen draw routine with cliprect
• Constantize variables
• Fix spacing
• Reduce unnecessary lines
• Suppress side effects for debugger read
• Fix ROM region namings
• Use C++ style comments for single line comments
• Fix main CPU ROM region size