[mc] Abstract the process and a snapshot types with a address_space superclass
Add a `address_space`, superclass of `process` and `snapshot`.
In order to do this, the contract of MC_process_read and
MC_snapshot_read has been uniformized:
* the order of arguments has been harmonized;
* a new flag MC_ADDRESS_SPACE_READ_FLAGS_LAZY is used to avoid copy
when the data is in the current memory;
* MC_NO_PROCESS_INDEX has been renamed into MC_PROCESS_INDEX_MISSING;
* MC_ANY_PROCESS_INDEX has been renamed into MC_PROCESS_INDEX_ANY;
* MC_PROCESS_INDEX_DISABLED is used to access the raw address space
(without privatisation support);
* `const void*` is used instead of `void*` when it possible.
Soem cleanup things are still to be done:
* remove special NULL handling;
* add support for SMPI privatization in the process object.
17 files changed:
