flightplans: Don't open all lua libs for security

[alamshafil]

Don't open all Lua libs, let the user manually import lib that are needed.

Affected code:

Avian/src/flightplans/flightplans.cpp

Lines 35 to 36 in 5aa0e4a

	// Make standard libraries available in the Lua object
	luaL_openlibs(L);