Template "methods".

Template "methods".

This helps current GDC, as it does not inline functions from modules
other than the current one (unless you use LTO or compile all modules
together).

But the real reason for the switch is not performance, it's the fact
that some library functions documented in the GIR files are not
present in the libraries. This means that if unused methods are not
discarded then linking every program using certain modules fails.

GC-sections would also be a solution, but using templates is more
portable.

Unfortunately the D frontend does not currently allow templates that
have the same name as functions, so mixins overloading existing
methods need to be changed. Hence no girtod runtime option allowing
turning this feature on/off.