Small reorganisation.

Autobuilder seems functional now. Can wipe out build/release/lib/rtl
and replace with autobuilder built rtl and tests all pass.

Removed shlibs. Instead: autoload DLLs, C++ includes, and
static libs live in lib/rtl, plugins in lib/plugins.

Will not work on Windows like this, but this can't be fixed
until we have a Windows dev.