Code review comment for lp:~widelands-dev/widelands/compiler_warnings_062017

I think we got rid of:
 * all problems with missing overrides / vitual
 * all unneed double promototions

We (well I) still see:
 * -Wformat-pedantic with printf and not void* pointers -> we should not use that flag
 * Problems with recursive macros, No idea about those, yet.
 * multiple instantiation of template functions/classes
    -> to much code is generated that must be eliminated when linking.
    Need SirVer or some other C++Guru to untangle that Template magic?
 * -Wcovered-switch-default problmes with covered switch default
    -> we should ignore these, If we fix it for llvm older gccs will start to complain :-(

Still this could go in, as we fixed auite a lot of warnings that have acuumulated
upto the boost.asi migration.

I will compile this again, and then play a bit if something is seriously broken.