Replace `include("bla.h")` with `Spring.Utilities.Bla`

[sprunk]

Including the file over and over in each gadget recreates the whole table (-> waste of cycles, garbage collector pressure) and pollutes the gadget with a ton of mostly useless globals.

For custom commands, the utilities table exists. Change

VFS.Include("LuaRules/Configs/customcmds.h")
Spring.Echo(CMD_FOO)

into

local CMD_FOO = Spring.Utilities.CMD.FOO
Spring.Echo(CMD_FOO)

2. create a Spring.Utilities subtable for other similar includes: keysym.h, colors.h[.lua] and apply the same treatment as above to gadgets.