Adding experimental parts to a KF5 library

[Kevin Kofler]

Ivan Čukić wrote:
> - 0 soversion to show that the library has no stable ABI.

I'd actually set both the soname and the fully-versioned name to 
libfoo.so.0.1, then if you change something binary-incompatibly, 
libfoo.so.0.2, etc. (or use libfoo.so.0.1 etc. as the soname and something 
like libfoo.so.0.1.0.0 as the fully-versioned name, if you really want to 
track binary-compatible changes too). Unlike libtool, CMake easily allows 
you to use such versioning, and it's really the right way to handle it. It 
allows both clearly identifying the library as preliminary (whereas 
libfoo.so.0 is also very commonly used for the first stable-ABI version of a 
library) and tracking binary incompatible changes in a sane way (without 
losing the zero major version).

        Kevin Kofler