remove unused include
fix #4495:

maps with mapinfo.lua but empty "mapfile" don't load
fix "make headercheck"
includes--
fix spring only listing the default openal device
PE: fix typo found by GF
reduce VA count again (discard GL4 streambuffer idea - it's slower)
PF: nlc equalize varNames between PE & PF (so they can in future share a single interface)
addendum
made "Duplicate AI Interface Info found" an error message:

because this mostly causes a crash!
equalize PE & PF further
fix "use before set"
AAI: make many class members private
move shared vars from PE & PF into an interface class
IPathFinder: move to interface ::ResetSearch()
AAI: use "default" header guards
AAI: get rid of all headers included everywhere:
only included required headers,
still everything seems to depend on everything :-(
AAI: fix win32 compile, initialize random generator only once
try to reduce count of CUtils compilation no. two
fix win32 linking / undefined symbols error