Temporal Entities definition

The first section of 
https://github.com/streamreasoning/RSP-QL/blob/master/Semantics.md needs 
some work. Currently we have:

"Temporal Entities:
Time |*T*| is defined as an ordered and infinite sequence of countable 
/temporal entities/ |(t_1 , t_2 ,...)|, where each |t_i ∈ *T*|. Temporal 
entities can be referred to as timestamps."

This cannot accommodate time intervals or multiple levels of 
granularity. I don't think we want, or need, to get into formally 
defining temporal entities.

Also "timestamp" is a role that a temporal entity can fill, relative to 
a timestamped graph.

Can we change this to:

"Let T denote the set of temporal entities. This specification is 
neutral regarding the formal specification of temporal entities."

and then add to the definition of timestamped graph

s a predicate that captures the relationship between the temporal entity 
|t| and the graph g.
=>
s a predicate that captures the relationship between the temporal entity 
|t|, called the timestamp, and the graph g

Tara