shmem: improvements

[Maxython]

The possibility of remote interaction with shmem is implemented, i.e. the shmem socket is multifunctional and can not only send data, but also start an action and update shmem data. This allows you to implement shmem actions close to the original system V shared memory from Linux. For example:

• Delete shmem if the process is not native
• Count the number of attached and process ids