MEDIUM: peers: handle arrays of std types in peers protocol

MEDIUM: peers: handle arrays of std types in peers protocol

This patch adds support of array data_types on the peer protocol.

The table definition message will provide an additionnal parameter
for array data-types: the number of elements of the array.

In case of array of frqp it also provides a second parameter:
the period used to compute freq counter.

The array elements are std_type values linearly encoded in
the update message.

Note: if a remote peer announces an array data_type without
parameters into the table definition message, all updates
on this table will be ignored because we can not
parse update messages consistently.