why we need these declarations sorted by version:
* dlopen() and dlsym() causes problems with GL sometimes.
-> it would be nice if we'd be able to replace this
* using gl*() functions directly causes even more problems: system A
compiles&&links boson but has GL version x, system B runs that binary, but has
GL version y with x != y.
-> we need to resolve functions on runtime, otherwise we may get
- not support special features of system B, if y > x
- not run at all, due to undefined references * glXGetProcAddressARB() might be a way out of this problem (yet to be tested at this point!), but it does not guarantee that it returns NULL if a function is not available -> we need additional checks for the available functions (e.g. using glGetVersion() and/or by checking for the extensions)
this is what we need these files for.