[Orxonox-dev] Relase compiling

[Reto Grieder]

Hi guys

You may have seen that there is a new CMake configuration: RelForDevs.
Basically it replaces RelWithDebInfo and that in turn should now be used 
for actual release making (or installing) if you want debug symbols.

The reason for this new mode is that we want two different actual 
release modes (Release and RelWithDebInfo) that have extra 
optimisations. For GCC, the extra time spent is not that much, but using 
Link Time Code Generation in MSVC has a huge impact. If you change 
something in a source files (not header file!) in 'util', then the 
compiler would have to generate ALL code again. That is very annoying.

So we also need another release mode for development purposes that 
compiles fast enough: RelForDevs.

What about MinSizeRel then? Couldn't we just abuse that? Yes, we could. 
But who would guess?

So please, in future use RelForDevs for release builds unless you want 
to make a package or an installation.

Hint: The ORXONOX_RELEASE macro is only active for Release, 
RelWithDebInfo and MinSizeRel. Use this to activate expensive 
optimisations. Originally the macro is independant, but it seemed 
confusion to have that as well. So we now simply have 5 build 
configurations.

greetings from Pittsburgh!
Reto