This commit separates the functionality of managed_rpc_type<T> into
dedicated lifetime management types and conversion functions. This
makes for clearer the code since it is now possible to know when
a conversion is performed.

Lifetime management for C-types is now done with the managed_ctype<T>
types, which act only as holders of dynamically allocated C types and do not
perform any type conversions whatsoever.

Type conversions are now done with the T1 convert(T2 obj) family of functions.
When converting from CXX to C API types, these functions effectively
return instances of the appropriate managed_ctype<T>s. If one wishes to
relinquish ownership of the content of the managed_ctype<T> (e.g. to
pass it to a pure C function that will release it), this can be done
with the managed_ctype<T>::release() function.

Fix missing definitions of ADM_register_pfs_storage, ADM_update_pfs_storage and ADM_remove_pfs_storage

This makes it much simpler to share type definitions between the library
and the daemons.

- C++ types are now declared in admire_types.hpp
- C & C++ types are defined in types.cpp. The reason for them being in
  the same file is that the C type-creation functions use logging
  facilities that are C++ code. Until we offer a C interface for them,
  C-type functions need to be compiled with a C++ compiler.

- `scord` daemon now has its own directory in `src/scord`
- `scord-ctl` daemon now has its own directory in `src/scord-ctl`
- library code now lives under the  `lib` directory
- public rpc definitions now live in `src/lib/rpcs/`
- private rpc definitions for each daemon now live in
  `src/scord/rpcs/` and `src/scord-ctl/rpcs/`, respectively
- `config`, `logger`, and `network` code now live under the `common` directory