Add macro compiler_repository to have early access to compiler name

See merge request mpcdf/osc-plugins!2

This can be used to disable multibuilds for certain compilers.

This avoids having to install two separate intel_parallel_studio
packages. It is probably also not a good idea anyway to inter-link two
of them at the same time.

Add aliases for mpcdf_set_as_branch, mpcdf_sync_projects

See merge request mpcdf/osc-plugins!1

Consequentially, the last arguments becomes deprecated, as it always
would be "software"

According to its own file

  include/crt/host_config.h

Enables zsh completion to find these commands. otherwise the output of
osc help is not correctly parsed.