Rename the "Library" into liblumierasupport.so

Rationale: this is the *support* Library.

The real "Lumiera-Library" does not exist yet.
liblumiera.so will be the *interface* every external
module / plug-in uses to get Lumiera functionality.

Especially the work on Library dependency clean-up
made outright clear, that this interface library
needs to be a separate piece of software, which is
carefully crafted, and more-or-less depends on the
whole application.